======================
Welcome to Freeciv 2.6
======================

The most important changes between major releases are shown below.
Not all changes are shown here. See NEWS-2.6 for changes in minor
releases since 2.6.0. Those who are interested in seeing even more
detailed changes should check the ChangeLog file.


MAJOR CHANGES FROM 2.5.x to 2.6.0
---------------------------------

   (from <http://www.freeciv.org/wiki/NEWS-2.6.0>, 2018-07-22)

   The major changes in Freeciv 2.6 are a redesigned Qt client, an updated
   civ2civ3 ruleset, and a whole lot of extra flexibility to create custom
   rulesets.

   As is usual for major releases, 2.6 clients cannot interoperate with
   pre-2.6 servers, and vice versa. Most pre-2.6 savegames can however be
   loaded into 2.6, and in most cases, the supplied rulesets have not
   changed so much as to make it difficult to complete a game started with
   2.5.x's rules.

Server / General

Changes affecting players (supplied rulesets)

   A new ruleset, "sandbox", is included (as of beta2). This is a place
   for developers to experiment with and demonstrate new engine features,
   without regard to game balance or savefile compatibility; sandbox games
   started in this version may not load into future releases (even minor
   2.6.x releases). HRM#696004

   Miscellaneous rule changes affecting all or most rulesets:
     * In most supplied rulesets, non-military units and some air units no
       longer impose a zone of control (ZoC). GNAPATCH#4818 GNAPATCH#4935
     * classic, multiplayer, experimental: Mines on Desert and Glacier are
       now Oil Wells, and can only be built once Construction and Refining
       are known respectively. If the underlying terrain changes between
       one supporting regular mine and one supporting oil well, the
       improvement is lost. (civ2civ3 is different, see below.)
       GNAPATCH#4391
     * Buoys no longer claim territory, and so can no longer be used to
       block travel during peace. GNAPATCH#3878
     * The size of barbarian uprisings, and the effect of the 'barbarians'
       setting, have changed. (It's not clear what the old code actually
       did.) GNAPATCH#5909
     * When 'autoattack' is enabled, now the best attacker goes first, not
       the worst. (This makes target-specific strength factors work to the
       attacker's advantage rather than the defender's, but does make it
       easier to lure out strong attacking units.) GNAPATCH#7942
     * (as of RC2) Bribe cost for damaged units has increased. Previously
       (due to a bug) it was halved if the unit had lost any hitpoints at
       all. Now it depends on how damaged they are (up to at most a
       discount of half, as before). HRM#763896
     * "Industrial Accident" disaster, where a Mfg. Plant can cause
       population loss and pollution. GNAPATCH#5014
     * When a Spy sabotages another diplomatic unit, there is no longer a
       diplomatic battle (which could lead to the elimination of the
       victim, rather than just a reduction in hit points). GNAPATCH#6103
     * "SDI Defense" now works against allies' nukes. GNAPATCH#6693
     * In rulesets where the Great Library grants techs known by other
       civilizations, it now grants a random tech of the eligible ones,
       rather than a predictable one. GNAPATCH#5104
     * Ruins are removed whenever the underlying terrain is changed.
       GNA#20898

   Rule changes to specific rulesets:
     * civ2civ3 has had many changes.
          + Units and combat
               o 'Tired attack' is enabled: units that attack with less
                 than one movement point have reduced attack strength.
                 GNAPATCH#7160
               o Units which cost population (Settlers, Migrants, and
                 Fanatics) no longer pay shield or gold upkeep. Instead,
                 they count towards the per-city food upkeep limit.
                 (Changed because the AI no longer mishandles this
                 combination.) HRM#681977
               o Naval units are now generally cheaper, to make the ratio
                 of strength to cost more similar to land units.
                 GNAPATCH#8124
               o Airplanes (fighters and bombers) can spend an extra turn
                 in the air, allowing more air-to-air battles. They lose
                 10% of hitpoints every turn when in the air, like
                 Helicopters. GNAPATCH#4812
               o Cruise Missiles have increased range, and can target
                 aircraft.
               o All aircraft can use Airports to travel between cities.
               o Carriers can now transport Land units (non-wheeled, and
                 non-merchant). (Because Carriers could already transport
                 Helicopters which can transport Land units. However, not
                 all land units can freely enter or leave Helicopters
                 while on board a Carrier.) HRM#681866
               o Only "Big Land" class units (tanks, artillery etc) kill
                 citizens when attacking a city; "Land" class units
                 (infantry etc) no longer do. GNAPATCH#7078 GNA#24616
               o Triremes are subject to ZoC when traveling on rivers, and
                 can no longer move diagonally between river tiles.
               o Explorers can establish embassies and investigate cities,
                 like Diplomats. They are slightly more expensive, but do
                 not become obsolete.
               o The actions Establish Embassy and Investigate City can be
                 done directly from a boat.
               o Diplomat and Spy can fortify (this provides no defensive
                 bonus, but means they don't wake up as they would when
                 sentried). GNA#25151
               o Reworked merchant units (Caravan and Freight) and trade.
                 GNAPATCH#7137
                    # No longer require river or roads to move.
                    # Subject to ZoC.
                    # Cannot establish trade routes or help build wonders
                      without movement points.
                    # No one-time trade bonuses when they enter a city.
                    # When war is declared between two players, existing
                      trade routes are canceled, and new ones can't be
                      established while a state of war exists.
                    # Can help building allies' or team-mates' wonders.
               o The default start units include a Worker instead of
                 Migrants. GNAPATCH#6368
          + Terrain and terrain alterations
               o Changes to defensive bases:
                    # New 'Fort' and 'Airstrip' bases, which must be built
                      before 'Fortress' and 'Airbase' respectively. They
                      provide some defense; airstrips provide a refuel
                      point.
                    # Fortresses and Airbases no longer prevent a whole
                      unit stack from being lost when one defender dies
                      GNAPATCH#5998; but they now provide some defense
                      bonus against all kinds of attacking unit.
                    # Airbases provide extra vision, like Fortresses after
                      Astronomy; and provide more hitpoint regeneration
                      (equivalent to a city without an Airport).
               o City centers once again always get automatic roads, even
                 on rivers without knowledge of Bridge Building.
                 HRM#676162
               o City center tiles are no longer guaranteed a minimum of 1
                 food. The only effect is that city center desert tiles no
                 longer give any food if a mine is built on them.
                 HRM#681856
               o Mountains now get an extra production point from mining
                 (changed from +1 to +2).
               o Desert and Glacier tiles can now have an oil well built
                 on top of a mine once Refining is known, for an extra
                 production point. The mines available from the start of
                 the game are drawn with the same sprites as on other
                 terrains. GNAPATCH#5915
               o In order to get a bonus with Offshore Platform, deep
                 ocean tiles now require the new extra Oil Platform,
                 rather than Buoy. Offshore Platforms now give a bonus
                 from lake tiles too.
               o Added Maglevs (with Superconductors), which supplement
                 Railroads and give infinite movement to certain units.
               o Forest, Jungle, and Swamp tiles now give the advertised
                 defense bonus of 25% (in 2.5 it was rounded down to 20%).
               o Forest and Jungle tiles can now suffer pollution and
                 fallout, like most other tiles. HRM#681860
               o Adjusted terrain transformations (that can be done once
                 Fusion Power is known). Designed so that all useful
                 alterations can be finished in 1 or 2 steps, and all
                 global warming effects can be reversed with Transform.
                 GNAPATCH#5596
               o Adjusted effects of climate change. Ocean can no longer
                 become Deep Ocean. GNAPATCH#5475
          + Buildings and wonders
               o Great Wonders are now only obsoleted when the owner
                 learns a certain technology, not when any player does.
                 GNAPATCH#5542
               o A new building, the Ecclesiastical Palace (available with
                 Theology), acts as a second center of government.
                 GNAPATCH#7159
               o Spaceship part cost approximately doubled. GNAPATCH#5996
               o It's no longer possible to build a Harbor next to a lake
                 (since it gives no benefit to lake tiles). GNA#25070
               o Conversely, Lighthouse and Magellan's Expedition can be
                 built next to deep ocean. GNAPATCH#7742
               o The suppression of Super Highways trade benefits by a
                 farmland bonus no longer applies to city center tiles.
                 HRM#695978
          + Technology
               o 'Holes' in the tech tree (knowing a tech without knowing
                 its prerequisites) are no longer allowed (previously they
                 could arise through tech trading, tech loss, and so on).
                 GNAPATCH#4967
               o Construction now requires Iron Working, rather than
                 Currency (so that Iron Working is a prerequisite for
                 Frigates and Ironclads). GNAPATCH#5999
               o Population pollution can now occur even without knowledge
                 of Industrialization. (This was a corner case that would
                 likely never have been encountered.) GNAPATCH#5015
          + Government
               o The Tribal government gives one content citizen per city
                 instead of martial law.
               o Tribal governments get an extra unhappy citizen at a
                 slightly smaller empire size, and Monarchies at a
                 slightly larger.
               o Each city in a Federation gets 2 extra luxury points.
               o The 50% science loss from Fundamentalism is now additive
                 with other science bonuses, rather than multiplicative.
                 (It's equivalent to losing a building such as a Library.)
               o Similarly, the luxury loss from Anarchy is now additive
                 rather than multiplicative.
          + Other
               o Certain buildings (and all wonders) generate culture
                 points every turn, which accumulate in a city (and change
                 hands with it); each nation can also get one-time culture
                 boosts from achievements such as mapping the entire world
                 or launching a spaceship. Culture affects score, and city
                 culture drives migration, if enabled. A cultural victory
                 is also possible (but not enabled by default, as these
                 effects have not yet been tested and balanced); a player
                 must have culture above a certain threshold, and a
                 convincing lead over other players, to win. GNAPATCH#5997
               o The outer ring of tiles worked by a city can be stolen by
                 an enemy border source. (The inner ring is permanently
                 owned by the city owner.) GNAPATCH#7096 HRM#651450
               o Adjustments to AI bonuses: HRM#681976 GNAPATCH#6006
                    # Hard AIs are no longer favored by other AI players,
                      but Cheating AIs are favored more.
                    # Cheating AIs no longer get any bonus to defense
                      (they used to get one against land attacks); but
                      their units do now cost more to bribe, they don't
                      pay unit food upkeep, they get a bonus to population
                      pollution, and their existing bonuses to veteran
                      chance and city incite cost are increased.
               o Tweaked the startup defaults. (These are almost all
                 server settings that can be customized to taste.)
                 HRM#650801
                    # Grant a diplomat start unit ('startunits').
                    # 6 players by default, not 12 (and a smaller map).
                    # Tweaked map generation: smaller poles, less shallow
                      ocean.
                    # Revolutions tend to become quicker the more times
                      any player has used the target government type
                      ('revolentype').
                    # Halved the chance of building destruction when a
                      city is conquered ('razechance').
     * multiplayer ruleset:
          + 'Tired attack' is enabled: units that attack with less than
            one movement point have reduced attack strength. GNA#22395
          + Darwin's Voyage now only gives one free tech, not two.
            HRM#692110
          + Buoys have been restored, now that they no longer claim
            territory. GNAPATCH#3874
          + Borders are now enabled by default; the 'foggedborders' option
            has been set so that you can't deduce enemy movements through
            their border changes; you can always see your own territory.
            GNA#17304
     * experimental ruleset:
          + One player policy, 'Personal Freedom', which allows trading
            off science against military unhappiness.
          + Culture sources (fewer than civ2civ3: Palace, Colosseum,
            Library, University). Cultural victory is enabled by default.
          + Explorers can establish embassies once Writing is known.
            GNAPATCH#5132
          + Spies can bribe and sabotage units which are not alone on
            their tiles. GNAPATCH#5295
          + Caravans and Freight can opt to not to establish (or displace)
            a trade route when arriving at a destination city, instead
            receiving just the one-time bonus ("Sell Goods").
          + Workers and Engineers can fortify.
          + Various achievements. They are only available to the first
            player to reach them, and have no gameplay effect.
          + AI traits are somewhat randomized. GNAPATCH#5226
          + The fourth city radius on square topologies is slightly
            larger. GNAPATCH#5983
     * civ1 and civ2 rulesets (to improve their fidelity):
          + A tile with both a river and a fortress now has a higher
            defensive bonus, as the bonuses are now multiplied rather than
            added (restoring the 2.4 behavior). GNA#23143
          + In the civ2 ruleset, Diplomats and Spies can now perform their
            actions directly from a ship on the ocean. GNA#23604
          + Player colors are by default tied to specific nations.
            GNAPATCH#3927
          + The civ1 ruleset no longer has Farmland (previously it existed
            despite being impossible to build, due to engine limitations).
            GNAPATCH#4342

   New/changed game settings:
     * A new option 'revolentype' controls how the period of anarchy
       during a revolution is determined. New options include a random
       period with a maximum other than 5 turns, and a period that
       decreases the more times anyone has switched to the target
       government. GNAPATCH#4700 GNAPATCH#5338
     * The 'diplcost' setting has been split into 'diplbulbcost' and
       'diplgoldcost'. GNAPATCH#5386
     * The 'huts' setting is now relative to map size (it was a count).
       Old scenarios will retain their behavior, but old server scripts
       will not. GNAPATCH#6669
     * The 'happyborders' setting has a new value which allows your units
       to be inside allies' borders without causing unhappiness.
       GNAPATCH#5001
     * The 'spacerace' and 'alliedvictory' options have been replaced by a
       new bitwise option 'victories'. A third flag has been added to this
       option to enable 'cultural victory' in rulesets which support it
       (currently 'civ2civ3' and 'experimental'). GNAPATCH#4017
       GNAPATCH#4018
     * 'citymindist' now goes up to 11. GNAPATCH#5572
     * The settings 'sciencebox' and 'killstack' can now be changed in the
       pregame of scenarios which have players defined (such as Europe
       1901).
     * 'startunits' can now include a ferryboat unit ('f'). GNAPATCH#4861
       Also, this setting can now be empty if 'startcity' is set.
       GNAPATCH#5887
     * Map generation:
          + The previous hard-coded behavior that non-wrapping maps had
            only a single pole has been replaced by a new setting
            'singlepole' which controls this behavior. GNA#23261
          + The previously hardcoded suppression of relief at the poles is
            now controlled by a new setting 'flatpoles'. GNAPATCH#6919
          + Narrower borders around edged maps (restoring 2.2.x behavior).
            GNAPATCH#6917
          + Map generation now tries a bit harder before giving up.
            GNAPATCH#4900

   Game limits:
     * The maximum number of regular players has increased from 126 to 150
       (160 including barbarians). GNAPATCH#4254
     * The maximum number of cities and units in a game (added together)
       has increased from 65535 to 250000. GNA#21950

   Supplied scenarios:
     * A new scenario, "Europe 1900 WWI", is included. This is a Europe
       map with the cities and units of the Great Powers prior to the
       outbreak of the First World War. (A previous version was available
       for 2.5 via the modpack installer, as "Europe 1901".) GNAPATCH#6434
     * The large Earth scenario now has 52 more start positions (for a
       total of 91), and players start with their first city built. Thanks
       to Rhue. HRM#688280 HRM#702265

Changes affecting other rulesets / modders

   We've tried to make it a bit easier for people not experienced with
   modding to add new nations to their local installation, with the
   'override' directory. How to use this is documented in
   doc/README.nations. GNAPATCH#3926

   Both client and server have a new command-line option --warnings,
   designed for modders, which warns about deprecated modpack constructs
   that may disappear in future releases. If you port a modpack to 2.6,
   it's a good idea to run with this option to check for old constructs.

   Ruleset authors can control much more of the game behavior. Comments in
   supplied ruleset files give some documentation and usage examples of
   new features; you can also browse the forum thread where most features
   were announced as they were added.
   <http://forum.freeciv.org/f/viewtopic.php?f=11&t=122>

   Existing rulesets need changes to work with 2.6; see
   <http://www.freeciv.org/wiki/How_to_update_a_ruleset_from_2.5_to_2.6>
   for a minimal recipe (not all required changes are listed below). Once
   you've updated to 2.6 format, the next major version after that is
   planned to contain a tool to upgrade rulesets automatically.
     * Extras
          + Most additions to base terrain -- roads, bases, and specials
            -- are now unified as "extras"; only resources remain
            separate. The properties and graphic representations of extras
            are now somewhat less tied to their category, although roads
            and bases continue to exist as subclasses with unique
            properties.
          + The previously hardcoded set of terrain specials -- mine,
            irrigation, farmland, pollution, fallout, hut -- is now fully
            under ruleset control.
          + Production bonuses and penalties formerly caused by terrain
            specials are now governed by new effects (Irrigation_Pct,
            Mining_Pct, Output_Tile_Punish_Pct), so can depend on more and
            different requirements. GNAPATCH#3965 GNAPATCH#3967
            GNAPATCH#3974
          + The set of events that can cause extras to appear and
            disappear (for instance user actions like "mine", "irrigate",
            and "clean fallout") is still fixed, although their mapping to
            extras is not. If the ruleset allows the same cause to create
            or remove multiple extras, the player can choose.
          + Any kind of extra (including roads and bases) can fall into
            any of the new extra categories (Infra, Natural, Bonus, or
            Nuisance). (This mainly affects how they are presented in the
            help and user interface.) For instance, it would be possible
            to have a base generated at game start like a hut (Bonus
            category).
          + The total limit on extras of any kind is now 64 (previously
            there were limits of 32 base types and 8 road types).
          + New features:
               o Bases on a tile in unclaimed territory can now have an
                 owner distinct from the border owner of the tile they are
                 on. This only has an effect for bases providing vision.
                 For example, this allows buoys to provide vision to a
                 player without also providing territory (and blocking
                 peaceful units). Unlike territory-providing bases, such
                 bases do not change hands, unless another base is built
                 on the same tile. GNAPATCH#3630
               o Extra removal (cleaning and pillaging) can now have
                 additional requirements (rmreqs).
               o The time taken to remove an extra can be extra-specific
                 (removal_time) or terrain-specific (via existing
                 clean_fallout/pollution_time or new pillage_time).
               o Extra build/removal time can now also depend on both
                 extra and terrain to some extent (build_time_factor,
                 removal_time_factor).
               o Extras can optionally disappear when the underlying
                 terrain changes even if they would be valid on the new
                 terrain -- 'TerrChangeRemoves' extra flag. GNA#20898
               o Optional defense layers -- 'Natural' and 'Fortification'
                 -- with multiplicative defense bonuses. Allows rulesets
                 to fix a regression in 2.5 when rivers were turned into
                 road types. GNA#23143
               o The move_mode of roads can now affect whether a move is
                 legal, not just its cost. For instance, a river-native
                 unit can be prevented from moving between two rivers on
                 diagonally adjacent tiles. GNA#16383
               o Integrating roads, allowing move bonus / legality between
                 two tiles with different types of roads. Graphics are
                 drawn appropriately. GNAPATCH#3829
               o Roads can have additional requirements on where they are
                 started (building road on a tile where no adjacent tiles
                 have the same or an integrating road) -- 'first_reqs'.
                 GNAPATCH#4688
               o Extras can now be native to units without also being
                 refuel points for them ('Refuel' extra flag).
                 GNAPATCH#4106
               o The names of menu options for building the two categories
                 of base with their own keystrokes are now under ruleset
                 control, rather than being fixed as "Type A / B base".
                 GNAPATCH#2721
               o The extras used for pollution, fallout, and huts can be
                 terrain-dependent and/or chosen randomly from a set.

     * Actions
          + Some actions performed by units -- in 2.6, just the special
            diplomat/spy/caravan actions -- can now be configured by the
            ruleset. The consequences of actions are still largely
            hardcoded, but the circumstances in which units can perform
            these actions are now specified with the requirements system
            using 'action enablers'. Many previously hard-coded rules are
            now under ruleset control. See doc/README.actions.
            Some examples of newly possible things (this is not an
            exhaustive list):
               o Helping to build a wonder in a foreign city.
               o Sabotaging a unit with 1 hitpoint can kill it.
               o Poisoning a size 1 city can destroy it.
               o Acting against units not alone on a tile (the player is
                 prompted to choose a target unit).
               o Acting against units inside cities (but you must be able
                 to see inside the city, implying at least Alliance).
               o Hostile actions against players you're not at war with,
                 or yourself.
               o Establishing embassies with No_Diplomacy nations.
               o Units don't have to have a Diplomat/Spy flag to perform
                 what have traditionally been diplomatic actions.
                 (However, these flags do still control the ability to
                 survive actions, defense against such actions, and city
                 resistance to tech stealing.)
          + One new spy-type action, "Steal Gold", which steals a random
            amount from the target player's treasury. New effects control
            the maximum amount stolen ("Max_Stolen_Gold_Pm") and how much
            is lost to both players ("Thiefs_Share_Pm"). GNAPATCH#5274
          + "Enter Marketplace" (one-time revenue from caravans, now
            called "Sell Goods" in most rulesets) can now be an
            independent action from "Establish Trade Route", with its own
            rules.
          + It's now possible to allow only targeted sabotage and tech
            stealing, without offering the option of a randomly chosen
            target.
          + Many new requirements have been added to express conditions
            that were previously hard-coded in these actions. See
            "requirements" below.
          + A Lua signal 'action_started_*' is emitted when an action is
            about to take place, allowing additional behavior to be added.
          + Since it's now possible to construct a ruleset where an action
            is illegal due to some restriction that is unknown to the
            player, a new effect "Illegal_Action_Move_Cost" allows
            movement points to be deducted if such an action is attempted.
            This is intended to avoid the information leak from such
            attempts being entirely without penalty (which would reward
            tedious action scrubbing by players).

     * Culture
          + New feature: the ruleset can award culture points points that
            accumulate over time ("history") or points that only last as
            long as a condition holds ("performance"); each can be accrued
            on a per-city or per-nation basis.
               o Rulesets control the numeric criteria for cultural
                 victory (which is optionally enabled with the 'victories'
                 setting).
               o Requirements can test the total culture of cities or
                 players.
               o Lua scripts can test or modify culture.
          + City culture can boost migration.
          + See the civ2civ3 description above for an example of what can
            be achieved.

     * Achievements
          + The game can track track whether players meet certain
            conditions (see doc/README.achievements), and award
            'achievements' either to the first or to each player that
            meets the requirements. Achievements can simply be trophies
            with no further effect, or can affect gameplay by granting
            culture points, through the effects system, or through Lua
            scripting.

     * Policies
          + Rulesets can define a set of 'policies', sliders which the
            player can adjust once per turn and which affect the game via
            'multipliers' in the effects system. These can be used to
            implement custom trade-offs similar to the built-in tax rates.

     * Disasters
          + A new disaster effect "ReducePopDestroy"; this is like
            "ReducePopulation" except that it can destroy a city of size
            1.
          + A new Lua signal 'disaster_occurred' (replacing 'disaster')
            tells a script whether the disaster had some effect inside the
            game engine. The default script does not implement any
            additional effects, so prints a message if there was no net
            effect from a disaster. GNA#22082

     * Terrain
          + Terrain defense bonuses that aren't a multiple of 10% now work
            as expected (previously they were rounded down to the nearest
            10%). GNA#25432
          + Map generation:
               o A new 'Frozen' terrain flag, which can apply to land and
                 water. Frozen terrain is generated near the poles;
                 terrain changes will try to preserve frozenness; and
                 rulesets can specify that freezing/thawing terrain
                 transformations require a certain threshold of
                 surrounding frozenness. These changes are intended to
                 allow rulesets to define 'sea ice' terrains.
               o Better support for multiple lake terrains: each lake
                 picks a consistent terrain type (rather than a
                 patchwork), and the NotGenerated flag is now honored for
                 lake terrains. GNAPATCH#6918

     * Units and movement
          + There have been a lot of engine changes, particularly in
            path-finding and AI, to support units with complex or unusual
            movement restrictions. If you tried to create an unusual type
            of unit or terrain restriction in a previous version and it
            didn't work very well, it's worth trying again. There are too
            many changes to list individually, but here are some of the
            more notable ones:
               o The 'shore bombardment' combat rule, where both attacker
                 and defender firepower are reduced to 1, now applies to
                 any situation where each unit couldn't move to the
                 other's tile. GNAPATCH#3830
               o Path-finding through unknown terrain makes different
                 decisions. GNAPATCH#3903
               o Auto-explore works better with units other than pure
                 land/sea units. GNAPATCH#4853
               o Unreachable target units are handled better by
                 path-finding. GNAPATCH#4985
               o As part of this, the old 'move_type' ruleset parameter
                 has been completely retired; the engine infers what it
                 needs from other unit properties. GNAPATCH#4865
          + Units no longer have to impose zones of control (ZoC); this
            can be disabled with the 'HasNoZoc' unit type flag. GNA#21507
          + The hardcoded rule that units may only impose a zone of
            control (ZoC) on land has been replaced by the 'NoZoc' terrain
            flag. GNAPATCH#4597
          + Ability to airlift a unit is now controlled by a unit class
            flag 'Airliftable', rather than being hardcoded to units the
            game thought were land units. GNAPATCH#3871
          + The hardcoded rule that units may fortify on land but not
            water has been replaced by the 'NoFortify' terrain flag.
            GNAPATCH#5075
          + A unit type may now both fortify (F) and build fortress-type
            bases (Shift+F). The new unit type flag 'Cant_Fortify'
            replaces the previous hardcoded rule that 'Settlers' type
            units could not fortify. GNAPATCH#5072
          + A new ruleset option 'pythagorean_diagonal' allows diagonal
            moves in square topologies to cost more than orthogonal moves.
            GNAPATCH#4819
          + The maximum paradrop range has been increased from 255 to
            effectively unlimited. GNA#24349
          + Rulesets now have better control over which unit types can be
            granted via 'startunits', with the '*StartUnit' role flags.
            GNAPATCH#4625
          + The maximum number of ruleset-defined unit type flags has
            increased from 16 to 32. GNAPATCH#4904

     * Cities
          + Rulesets can now control how many of the tiles initially
            claimed by a city are immune from later border stealing, via
            'radius_sq_city_permanent'. GNAPATCH#6036
          + A new tech flag 'Claim_Ocean_Limited' which allows cities and
            bases to claim water tiles only if they themselves are in
            water (unlike 'Claim_Ocean', which also allowed land cities to
            extend claims over water). GNAPATCH#4629
          + The effect where city disorder spills over into national
            revolution now works at city resolution, as does the number of
            turns of sustained disorder required, which is now under
            ruleset control (new 'Revolution_Unhappiness' effect replacing
            'Revolution_When_Unhappy'). GNAPATCH#4021
          + Building obsolescence is now defined with a list of any
            requirements (rather than restricting buildings to being made
            obsolete by tech and replaced by other buildings), with any
            fulfilled requirement making the building obsolete.
            GNAPATCH#3941 GNAPATCH#1341
          + The "Visible_Walls" effect is no longer boolean; with the
            cooperation of the tileset, it allows up to 7 different wall
            graphics to be selected (which don't actually have to be
            wall-related). GNAPATCH#4393

     * Trade
          + Trade route legality / bonus can now differ depending on
            whether foreign trade routes are with an enemy, ally, or team
            member. GNAPATCH#4499
          + Whether trade routes give a one-time bonus to gold and/or
            science is now configurable. GNAPATCH#5248
          + The new 'Traderoute_Pct' effect allows ongoing trade route
            revenue to be adjusted. GNAPATCH#3249

     * Technology
          + Rulesets can control whether 'holes' in the tech tree (techs
            without their prerequisites) can ever appear due to various
            causes (tech trading, tech loss, etc). GNAPATCH#4415
            GNAPATCH#4789
          + The "Tech_Parasite" effect (traditionally used for the Great
            Library) now grants a random tech from those eligible, rather
            than the one defined first in the ruleset. GNAPATCH#5104

     * Nation styles
          + The 'city styles' that players selected when picking a nation
            have been replaced with 'nation styles'.
          + The graphics used for cities can still depend on these (via
            the new "Style" requirement), but don't have to; the sprite
            used for the city can depend on other properties of the city.
            (For instance, this can be used for ocean cities, so
            oceanic_graphic definitions have been removed.)
          + Music styles (see "Sound" later) can also be influenced by
            nation styles.

     * Barbarians
          + A new barbarian type, "Animal", is available for use by
            rulesets.
               o One Animal Kingdom AI "barbarian" player is created at
                 game start to manage the animals.
               o Each terrain type has just one characteristic animal (or
                 none); so for any given terrain there's one kind of
                 animal that'll spawn there, but a given animal can call
                 multiple terrains home (so if both Hills and Mountains
                 have animal="Mountain Lion", then wild lions will roam
                 inside any contiguous region of uplands, but will never
                 step/attack outside). Animals cannot conquer cities.
               o Animals' movement restriction to terrain is a property of
                 the owner, not the unit; so if an animal-type unit can be
                 captured it can then be moved anywhere, subject to the
                 usual rules.
               o The map is randomly populated with animal units according
                 to map size and terrain availability at game start
                 (controlled by the new 'animals' setting).
               o Animals do not respawn, and once they're all gone,
                 they're gone (as is the animal player).
          + The behavior of barbarian units -- when they 'retire'
            (disappear) -- is now more under ruleset control. A new
            effect, 'Retire_Pct', influences this.
          + The 'barbarians' setting is automatically adjusted and locked
            if the ruleset does not define any barbarian nations.
            GNAPATCH#7192

     * Effects and requirements
          + New requirements:
               o Requirements that depend on properties of a specific
                 unit, not just the unit type and location. These were
                 introduced mainly for use in action enablers, but can be
                 used in other situations (e.g. 'Veteran_Combat' effect).
                    # Whether a unit is currently being transported
                      (UnitState = Transported) or can exist independently
                      at its current location (OnLivableTile).
                      GNAPATCH#4983, GNAPATCH#4894
                    # The unit's veteran level (MinVeteran). GNAPATCH#4902
                    # The unit's remaining movement points (MinMoveFrags).
                      GNAPATCH#5033
                    # The unit's remaining hit points (MinHitPoints).
                      GNAPATCH#5135
               o 'DiplRel' requirement, allowing testing relationships
                 between the two players in some effects. Includes regular
                 diplomatic states (war, peace, alliance, team etc) as
                 well as shared vision, embassies, casus belli (reason to
                 cancel treaty), and whether they are in fact different
                 players. GNAPATCH#4051
               o The 'MaxUnitsOnTile' requirement allows testing the total
                 number of units currently on the tile. GNAPATCH#4224
               o New requirement 'Age' allows testing how many turns a
                 unit, city, or player has existed. GNAPATCH#5305
                 GNAPATCH#5380
               o 'NationGroup' allows testing whether a player is one of a
                 particular subset of nations. Rulesets can define nation
                 groups which don't appear in the nation selection UI, for
                 use with this requirement. The supplied rulesets define a
                 'Barbarian' nation group for this purpose. GNAPATCH#5383
               o 'Topology' tests properties of the game's map topology
                 ('WrapX', 'WrapY', 'Iso', or 'Hex'). GNAPATCH#6193
               o A new value 'Claimed' for the 'CityTile' requirement
                 allows testing whether a tile is inside any player's
                 borders. GNAPATCH#5929
               o 'BaseFlag', 'RoadFlag', and 'ExtraFlag', allowing testing
                 whether extra has certain properties rather than just its
                 type. GNAPATCH#3832 GNA#24445
               o The new requirement 'Extra' replaces 'Special', 'Base',
                 and 'Road'.
          + New requirement ranges:
               o 'Alliance' and 'Team' allow testing whether any player in
                 these sets has a particular property. GNAPATCH#4231
                 GNAPATCH#4388
               o 'Traderoute' allows testing whether any city with which
                 this one has a trade route has a particular property.
                 GNAPATCH#4459
          + The maximum number of requirements has increased from 10 to 20
            (to allow room for nreqs to be converted to present="FALSE"
            reqs; nreqs are now deprecated).
          + Effect changes not listed elsewhere:
               o The new 'Victory' effect allows the ruleset to add any
                 win conditions that can be expressed with the
                 requirements system. GNAPATCH#4151
               o 'Unit_Bribe_Cost_Pct' allows bribe cost to be adjusted.
                 Bribe cost reduction for settler-like units is now under
                 ruleset control. GNAPATCH#3412 GNAPATCH#4121
               o The 'Nuke_Proof' effect can now depend on diplomatic
                 relationship. GNAPATCH#6693
               o 'Pollu_Pop_Pct_2' replaces the tech flag
                 'Population_Pollution_Inc' for adjusting the pollution
                 caused by city population, so that population pollution
                 can be entirely independent of technology. GNAPATCH#5015

     * Calendar
          + Rulesets can now define sub-year divisions in their calendar.
            The new 'Turn_Fragment' effect controls how many fragments
            pass each turn. GNAPATCH#5249

     * Documentation
          + A long description file can be included in a ruleset, and is
            displayed in the client help.
          + Ruleset authors now have more control over when autogenerated
            help is displayed, via the 'quiet' attribute on requirements,
            actions, and combat bonuses. This allows suppression of
            autogenerated help text where it's inaccurate or misleading or
            the author would prefer handwritten text. GNAPATCH#4723
            GNAPATCH#7046
          + Unit classes can have custom help text. GNAPATCH#5834
          + Rulesets can contain a version number field, which is reported
            in help, on the metaserver, saved in savegames, etc.
            GNAPATCH#4734 GNAPATCH#4761

     * Lua scripting
       While old scripts should mostly continue to work, see
       <http://www.freeciv.org/wiki/How_to_update_a_lua_script_from_2.5_to_2.6>
       to avoid deprecated constructs. See the Events Reference Manual
       <http://www.freeciv.org/wiki/Events_Reference_Manual> for full
       documentation.
       Below are additions which are not covered in other sections:
          + Updated scripting engine from Lua 5.2 to 5.3.
          + Lua access to AI trait values. GNAPATCH#6557
          + (Terrain):class_name() ("Land" or "Oceanic") GNAPATCH#4746
          + (Direction):next_cw(), next_ccw(), opposite() GNAPATCH#5415
          + (Unit):kill()
          + give_tech(), giving control of penalty and notification; old
            give_technology() is deprecated.
          + New "pulse" signal, which is called every so often during a
            game. GNAPATCH#6286
          + Utilities for team pooled research: notify.research() /
            notify.research_embassies(), for notifications involving every
            one of a group of players that share research (possibly a
            team) GNAPATCH#6545 GNA#24056; and
            (Player):research_name_translation()/research_rule_name(), to
            name that group GNAPATCH#6603.
          + New 'city_transferred' signal, which is triggered whenever a
            city changes hands for any reason. 'city_lost' is deprecated
            in favor of this one. GNAPATCH#6673
          + New 'city_size_change' signal, superseding 'city_growth' and
            allowing script reaction to famine, etc. GNA#24115
          + Methods to test some city properties: (City):is_happy(),
            is_celebrating(), is_unhappy(), is_gov_center(), and
            is_capital(). GNAPATCH#6804
          + Methods to navigate unit transport stacks:
            (Unit):transporter(), (Unit):cargo_iterate(). GNAPATCH#6845
          + (as of RC2) find.role_unit_type() can now find a unit with a
            given flag, as well as a given role. HRM#700906

   Sound has had some major changes.
     * Musicsets are now separate from soundsets, which now just cover
       sound effects. Clients can select and disable the two
       independently.
     * Musicsets can specify soundtracks for pregame, victory, defeat, and
       in-game according to 'music styles' defined by the ruleset. In-game
       music is further divided by mood (currently 'peaceful' or
       'combat'). Ruleset Lua scripts can also cause specific music to be
       played. Supplied rulesets define music styles corresponding roughly
       to city styles ('Babylonian', 'Renaissance', 'Industrial', etc).

   Tileset authors have a few new facilities. Existing tilesets need
   changes to work with 2.6 at all; see
   <http://www.freeciv.org/wiki/How_to_update_a_tileset_from_2.5_to_2.6>
   for a minimal recipe.
     * As noted in the ruleset section, with the ruleset's cooperation, a
       tileset can have different graphics for different cities in a
       nation, and several different kinds of city-wall-like variants.
     * Can have different mine/irrigate activity icons for transforming
       terrain (unit.plant, unit.irrigate) and building extras
       (conventionally unit.mine, unit.irrigation). GNA#24329
     * Activity icons for removal of pollution/fallout type extras can be
       specific to the extra type. GNAPATCH#4235
     * Can specify an alternative layout for unit upkeep sprites
       ('unit_upkeep_small_offset_y'), for better display in the SDL
       clients. GNAPATCH#6564
     * Various elements now have configurable offsets, allowing more
       condensed graphics files.
     * Can specify seperate pixel_border_x/y. GNAPATCH#5786
     * Tilesets can have a summary and description, which are displayed in
       the client in "About Current Tileset". GNAPATCH#6350

   Scenario creators also have a few new features available. (Scenarios
   created with previous versions should continue to work in 2.6.)
     * Scenario property "Prevent New Cities"; players cannot build cities
       in such scenarios. Ruleset authors can give certain units a flag
       'NewCityGamesOnly', which prevents those units from being built in
       such scenarios, if that wouldn't make sense. (However, none of the
       supplied rulesets set this flag; in principle Settlers can be used
       for other things, although they cannot build cities in these
       scenarios.) GNAPATCH#5678 GNAPATCH#6424
     * Saltwater ocean flooding freshwater lakes can be disabled for
       specific scenarios. GNAPATCH#6994
     * There's an optional 'authors' property. GNAPATCH#6450
     * Scenarios can be marked as 'handmade', causing a warning about data
       loss when modifying them in the built-in editor. GNAPATCH#5608
     * It's now possible to set a player's government type in the editor.
       GNAPATCH#3300
     * Scenarios saved from the editor tended to be saved with fixed
       game/map random seeds which affected play. This no longer happens.
       GNA#24319
     * Scenarios are now saved with the version number of Freeciv that
       created them. When several scenario files with the same name are on
       the path, the client shows only the newest one that is still
       compatible with the client version.
     * A new server command '/scensave' is included as standard, to create
       a savegame suitable for use as a scenario. Previously this was only
       included in debug builds; it does the same as "Save Scenario" in
       the editor GUI. GNAPATCH#5755

Changes affecting server operators

     * It's now possible to /create an AI player with specified AI type
       but random name/nation. GNAPATCH#5259
     * New/changed server settings:
          + 'persistentready' allows control of whether a new player
            joining in pregame resets everyone else's "Ready" status
            (previously it always did). With the new setting 'connected',
            a player's "Ready" status will persist as long as they remain
            connected to the server. GNAPATCH#5978
          + The 'autosaves' option now has a value 'TIMER', allowing a
            periodic backup even if the turn has not changed. Frequency is
            controlled by a new setting 'savefrequency'. GNAPATCH#4379
          + 'scoreloglevel' controls whether AI players are included in
            the scorelog. GNAPATCH#5727
     * The server now tracks whether a setting has been explicitly set
       (even if to the same value as the default). This status can be
       reset with the new '/default' command. Its main effect is that
       savegames do not include default settings, allowing changes in
       engine defaults to affect existing games.

General

     * The implementation of research has been substantially reworked.
       This should have little visible effect, but may have fixed bugs,
       particularly with team pooled research.
     * There have been a lot of changes to path-finding to support more
       complex unit movement rules. There are quite likely to be behavior
       changes but, again, hopefully these only make things better.
     * Improvements to persistence across network disconnection and
       save/load cycles:
          + Open treaties still under discussion are now saved in
            savegames. GNA#22712
          + Demographic/score information from the start of a turn is now
            saved, so that it does not change after a save/load cycle
            mid-turn. GNA#22710
          + The history report is now saved, and sent to players who join
            mid-turn. GNAPATCH#6195
          + Whether a player has ended their turn is saved; this can avoid
            an extra turn delay when 'turnblock' is disabled, players
            disconnect between turns, and the game is reloaded.
            GNAPATCH#6192
     * Various dotfiles that lived directly under the user's home
       directory now live under the ~/.freeciv/ directory -- notably
       client settings (.freeciv-client-rc-*) GNAPATCH#4387 and server
       command-line history (.freeciv-server_history) GNAPATCH#5413.
     * The FREECIV_PATH environment variable is now deprecated; it will
       stop working entirely in the next major version. Use more specific
       variables like FREECIV_DATA_PATH instead. GNAPATCH#6279
     * Loading saved games from Freeciv before 2.0.x is no longer
       supported. GNAPATCH#3858

AI

   There is a new AI level, 'Handicapped'; this has the same inherent
   behavior as 'Novice', but is intended to suffer from additional
   ruleset-defined penalties. In most of the supplied rulesets it suffers
   penalties to science, defense, unit and city bribe cost, migration, and
   trade routes (but in civ2civ3 it instead only suffers trade and shield
   penalties). GNAPATCH#4599 GNAPATCH#4605

   Known issue: unfortunately, the current AI doesn't handle Fighter-type
   units (non-missile units with a single turn of fuel) at all well, so in
   this version it has been inhibited from ever building them. (Note
   however that civ2civ3 Fighters no longer fall in this category.)
   GNAPATCH#4927 HRM#658896

   As part of the path-finding rework, the AI is generally less restricted
   to use units with certain movement types for certain roles.

   There have been many other improvements to the standard AI's behavior:
     * Defense
          + The AI is now more likely to build defender units for
            undefended cities. GNAPATCH#6534
          + The AI was not building defender units when it wanted a
            defense building but was frustrated. GNAPATCH#5471
          + The AI was overoptimistic about defense strength when choosing
            what defender to build. GNAPATCH#5470
          + The AI has a more nuanced understanding of which buildings
            defend against particular unit types. GNAPATCH#4797
          + The AI no longer considers harmless units (such as civilians
            and those that can't attack) a danger. GNAPATCH#4821
          + If an AI diplomatic unit can't bribe a nearby unit in
            self-defense, it will consider sabotaging it instead.
            GNAPATCH#4153

     * Attack
          + The AI is more willing to build attacker units. GNAPATCH#6307
          + The AI now prioritizes particular cities for conquering.
            GNAPATCH#6430
          + If the AI has some bonus causing it to build veteran units,
            and the units thereby get a movement bonus, the AI is more
            likely to take this into account in its planning.
            GNAPATCH#4971

     * Economy
          + Autosettlers (for both AI and human players) now evaluate
            improvements on unworked tiles differently from tiles already
            being worked by cities. This fixes a pathology where
            autosettlers would prefer improving hills without coal to
            those with, and generally makes them less obsessed with
            mining. GNA#21437
          + If a city's food store is full and it is blocked from growing,
            the AI will prioritize production rather than food.
            GNAPATCH#3697
          + The AI will now build military units purely for their martial
            law effects. GNAPATCH#3989
          + The AI likes to build great (unique) wonders more than it used
            to. HRM#661176 Once it's started, it's less likely to stop.
            HRM#662556
          + The AI is willing to build workers and city founders in its
            designated 'wonder city', easing a pathology when that is the
            only city capable of building such units. HRM#660089
          + The AI tended not to switch from building units to buildings,
            even though it suffers no penalty for doing so. GNAPATCH#7312
          + General improvements in AI's evaluation of building
            usefulness. GNAPATCH#4885
          + AI players will now consider establishing trade routes with
            peaceful nations, not just allies (although allies are still
            preferred). GNAPATCH#6418
          + AI cities will not build endless caravans if already built
            ones are piling up. GNAPATCH#7570
          + The AI's selection of ferries for settler units is improved.
            GNAPATCH#4862

     * Research
          + The AI considers researching technologies for effects that
            they grant directly. GNAPATCH#4944

     * Government
          + AI now evaluates governments' effects directly, relying less
            on ruleset hints to choose a government. GNAPATCH#5331

     * Misc
          + Hard and Cheating AI players no longer automatically offer
            cease-fire at first contact (although they may well offer one
            shortly afterwards, or accept one, this is not automatic).
            GNAPATCH#6203

   There has been some work on the 'threaded' AI variant. One change is
   that cities only request tasks that current units can do. This improves
   performance, but no longer drives acquisition of new kinds of units.
   GNAPATCH#5496

   The stub AI can now be linked in statically. This makes it easier to
   set up a game where effective AI players are prohibited. GNAPATCH#7388

   AI behavior is also now somewhat more configurable by rulesets:
     * AI traits can now be specified as ranges; a value for each trait
       will be picked randomly at game start, if enabled by the new
       'traitdistribution' server setting. This is possible for the
       classic and civ2civ3 rulesets, and enabled by default for the
       experimental ruleset.

   The following changes are mainly relevant to AI developers:
     * Various new methods have been added to the AI callback interface.
       See the change log in doc/README.AI_modules for more information.
     * AIs now explicitly signal when they have finished their turn. As a
       result, the threaded AI can be used in autogames (timeout -1).
       GNAPATCH#4171
     * A new player created by civil war gets the same AI type as the
       victim. GNAPATCH#4828
     * The 'experimental' skill level, which is a hook for AI developers
       that in our distributed code does nothing different from hard AI,
       is now only included in --enable-debug builds. GNAPATCH#5466
     * There's a new autogenerated header freeciv_config.h, designed
       (unlike fc_config.h) as a 'public' header that's safe to include in
       external projects that build against Freeciv source (such as AI
       modules). It contains selected facts about how Freeciv was built,
       while trying not to cause namespace clashes / pollution.
       GNAPATCH#5419

Clients

   The Qt client has been more or less entirely rewritten; see below.

   Other client changes:
     * The Gtk3 client is now the default. Some new features have not been
       backported to the Gtk2 client.
     * New versions of clients with no user-visible differences, just to
       keep up with new library versions (these are not promoted for
       Windows for now):
          + There is a new "Gtk3.22" client. This has feature parity with
            the regular Gtk3 client (which supports Gtk as old as 3.8),
            but benefits from not having to be backward compatible. If you
            have Gtk 3.22, consider using this instead of Gtk3. (Gtk 3.22
            is a long-term stable release in the new Gtk+ versioning
            scheme.)
          + There is a new SDL2 client. This is a straight port of the
            existing SDL client from the SDL1.2 API with no new
            functionality. The SDL2 library has better support for
            hardware acceleration and new platforms. SDL1.2 support will
            be removed in the next major release.
     * Some clients have support for scaling the map graphics. This is
       implemented in a couple of ways; in both cases it is accessed via
       the +/- keys.
          + The Gtk3 client has (still somewhat experimental) render-time
            zoom. For now this is restricted to 2x magnification.
          + The Qt and Gtk2 clients have a simpler implementation where
            every time the zoom level is changed, the tileset is reloaded,
            so changing zoom level is slower, but all further redraws are
            without any delays; all other parts of the game UI are scaled
            too (so the city map area doesn't look as good).
     * The client now chooses a tileset automatically based on the map
       topology. Different preferred tilesets can be set for each
       topology. It should now be much harder to end up with a mismatched
       tileset and map topology by accident. GNA#16668
     * It's now possible to specify work for autosettlers to do ('worker
       tasks') by right-clicking on the city dialog map. Only supported in
       Gtk3 and Qt clients.
     * Units that pop up a menu of actions (such as diplomats and
       caravans) now only do so when focus reaches them, and the menu can
       be temporarily dismissed and will return.
     * When there are multiple possible transports for a unit, it's now
       possible to choose which one the unit is loaded onto. Currently
       this is only supported in the Gtk3 and Qt clients.
     * Goto path drawing has been reworked. The goto path now shows turn
       boundaries, waypoints, and whether the unit will have movement
       points at the end of the journey. GNAPATCH#5233 For patrol orders,
       the return path is shown. GNA#22692
     * Some action keys have changed, as a result of generalization of the
       game engine:
          + The shortcut for building fortresses and similar bases has
            changed from F to Shift+F, to allow a single unit type to do
            both. Similarly the key for building an airbase has changed to
            Shift+E.
          + The "Diplomat/Spy Actions" menu item has been renamed to
            "Do...", and now prompts for a target. (The associated key is
            still 'D', and pressing 'D' twice in succession specifies an
            action against the unit's current tile, as 'D' did in previous
            versions.)
     * Some actions have been renamed in the user interface, although
       their effects have not changed:
          + The "Enter Marketplace" action has been renamed to "Sell
            Goods" in most rulesets, to make it clearer that the
            Marketplace building is not relevant. GNA#24463
          + The act of a Spy stealing technology (where the technology can
            be chosen) is now known as "Industrial Espionage", to
            distinguish it from "Steal Technology" (which now refers to
            untargeted stealing).
          + The action of transforming terrain by pressing the 'Mine' key
            (for instance, turning Grassland into Forest) is now referred
            to as 'Plant'. GNAPATCH#4382
     * A new option to suppress autocentering and animation for automated
       units (such as autosettlers). GNAPATCH#7474
     * The Gtk and Qt clients now show icons with event messages.
     * When a city has negative production, its production text on the
       main map becomes red. GNAPATCH#8053
     * When loading a savegame, sounds are no longer played for events
       whose messages are displayed from the cache but took place in
       previous turns. GNA#24152
     * The full-screen preference is now saved separately for each
       different client type. GNAPATCH#5490
     * The city report now has a "continent number" column, mainly to
       allow sorting such that cities on the same continent are grouped
       together. GNA#23624
     * Player colors are now shown in the pregame screen (Gtk and Qt
       clients).
     * The client now sends periodic 'heartbeat' packets to the server, to
       make it more obvious when a connection has failed if there is no
       other activity. GNA#19561
     * A new option to remember the last server connected to. GNA#21752
     * When the server is unresponsive for a long time during turn change,
       clients now show an estimate as to when it will finish. (This is
       simply based on how long the previous turn took, so can be wrong.)
       GNA#14585
     * Client settings (such as tileset and menu music) are now available
       from a button on the start screen of the Gtk and Qt clients.
       GNAPATCH#4764
     * (Gtk3) The allowed ranges for the city governor can now be
       adjusted. GNAPATCH#6352
     * (Gtk3) On a completely fresh installation, the Gtk3 client adjusts
       some of its default settings ("arrange widgets for small displays"
       and fullscreen) to be suitable for the display size at the time it
       is first run. (Thereafter, the settings must be changed manually if
       desired, even if a different size display is used.) GNAPATCH#5459
       GNA#23988 There is a new '-- --resolution' option to influence the
       display size assumed for this and other display-size related
       adjustments (mainly for debugging).

Qt client

   The rewritten Qt client, which has a focus on fast-paced multiplayer
   games, has a completely redesigned user interface. There are too many
   changes to list individually, but here are some highlights:
     * Configurable keyboard and mouse shortcuts.
     * An optional popup window showing the outcome of unit battles.
     * Can pre-select action for spies, diplomats, etc to take.
     * "Units Filter" menus replaced with "Advanced unit selection"
       dialog.
     * Can quickly cycle map viewpoint over units/cities/capitals by mouse
       wheel over Units/Cities/Nations button respectively (wheel up =
       foreign, wheel down = yours).
     * Shortcut to buy city production by clicking on map.
     * Easy viewpoint switching for observers (right-click Nations
       button).
     * More integrated help. Ruleset help is shown throughout the game UI.
     * Savegame preview.
     * Can save the whole client map view as an image.
     * Improved keyboardless goto - units can be ordered to goto even when
       in a city.
     * Buttons with icons for unit orders on the main map view (similar to
       the SDL client).
     * Replaced tax rates dialog with a single bar with two sliders.
     * Three UI themes.
     * Fonts are automatically configured the first time the new client is
       launched, depending on screen resolution and DPI.
     * Requires at least Qt 5.2.
     * Features oriented to multiplayer games (on the 'Multiplayer' menu).
       (These are currently client-side features, so their state is not
       saved over a disconnect/reconnect or in savegames.)
          + Delayed goto: a set of unit goto/attack orders can be set up
            on the client, which will be sent to the server in one go.
            GNAPATCH#6743
          + Quick airlift: with a single click, airlift as many units of a
            specific type as possible from other cities to the target
            city. GNAPATCH#7472
          + Rally points: can specify that newly built units go to a
            particular tile. GNAPATCH#7465
          + Trade planning: suggest trade routes between a set of cities
            (including those not yet built), and automatically send
            caravans to implement the plan. GNAPATCH#6775
          + "Wake up": the client can play a sound on receiving a specific
            string. GNAPATCH#6648

Tools

   This version includes the beginnings of a graphical ruleset editor,
   "freeciv-ruledit"; however, it doesn't yet allow much editing. It can
   rearrange the order of technologies in an existing tech tree, rename
   units, buildings, and techs, and save a working ruleset; it can also be
   used to check statistics of a ruleset, showing how many techs, units,
   buildings, extras, etc a ruleset has.

Modpack installer

     * Modpacks may now depend on other modpacks, which are automatically
       installed if necessary. GNAPATCH#4479
     * Modpack specifications may now contain relative URLs, allowing them
       to be copied from one server to another without modification.
       GNAPATCH#4618 GNAPATCH#7376
     * The modpack installer can easily be built pointing to a different
       modpack list server (--with-modlist). GNAPATCH#4735

Tilesets, Art, etc

     * New large hex tilesets: Hexemplio (essentially the Ampliohexbig
       modpack, based on Amplio2) and Toonhex (like Hexemplio but with
       oriented units from Cimpletoon).
     * The game ships with the 'stdmusic' musicset, which contains the
       menu music previously in the 'freesounds' soundset. (It does not
       include any in-game soundtrack.) GNAPATCH#4753

Translations

     * Updated Polish, French, Catalan, Finnish, Russian, Spanish,
       Japanese, and British English localizations.

Build/portability

     * Clients now build against SDL2_mixer by default (apart from the
       SDL1.2 client). GNAPATCH#5119
     * It's now possible to use a preinstalled 'tolua', making
       cross-compiling easier. Preinstalled 'tolua' and Lua installations
       are used by default where available.
     * The standard Windows builds now require at least Windows Vista.
       GNAPATCH#6818
     * The Windows version can now build against the newer MSYS2
       environment instead of the obsolescent MSYS1. This will allow us to
       ship much newer (more featureful and hopefully less buggy) versions
       of the libraries we depend on, enable IPv6, create 64-bit builds,
       etc, but will only run on Windows 7 or later. For now, the standard
       Windows packages remain built with MSYS1, although experimental
       MSYS2 builds are available.
     * It's now possible to disable use of bz2/xz libraries even if they
       are found (--disable-libbz2, --disable-liblzma). GNAPATCH#7023
     * Work toward being able to compile with tcc. The server has been
       seen to compile; the client does not yet.
     * GGZ Gaming Zone support, which had been rotting for some time, has
       been removed. GNAPATCH#4680

   See doc/README.packaging for more information.

Known issues

   Here are some of the notable outstanding issues that we already know
   exist as of 2.6.0:
     * As noted above, the AI currently doesn't build Fighter-type units
       in classic rulesets. This is not currently expected to be fixed in
       2.6.
     * Turn change in AI games has got slower; we suspect this is a result
       of action generalization.
     * There's some evidence that autosettlers have got less effective.
     * Some bugs in the goto UI, particularly with fueled units like
       airplanes. Sometimes it is necessary to move units manually with
       the direction keys. e.g. HRM#765380, HRM#765079
     * The new tileset selection arrangements can still be a little
       confused/confusing. HRM#685235
     * The Gtk3 clients' theming has bugs with recent versions of Gtk3.
       HRM#693382
     * The Gtk3 clients' zoom function still has some glitches. HRM#696027
     * The Gtk3 clients currently don't have animation for moving the map
       view. HRM#735217
     * The SDL2 client is still more flakey than SDL in various ways.
     * The SDL clients have no UI for manipulating policies. HRM#657404
     * We suspect there are still some bugs lurking in the music
       soundtrack system.


MAJOR CHANGES FROM 2.4.x to 2.5.0
---------------------------------

   (from <http://www.freeciv.org/wiki/NEWS-2.5.0>, 2015-03-14)

   The main changes in Freeciv 2.5 are the inclusion of the 'civ2civ3'
   ruleset, a new Qt client, and much more flexibility for those creating
   their own rulesets. The AI has also had some improvements.

   As is usual for major releases, 2.5 clients cannot interoperate with
   pre-2.5 servers, and vice versa. Pre-2.5 savegames can however be
   loaded into 2.5, and in most cases, the supplied rulesets have not
   changed so much as to make it difficult to complete a game started with
   2.4.x's rules.

Server / General

Changes affecting players (supplied rulesets)

   A new ruleset civ2civ3 is included, an evolution of the civ2_3 ruleset
   by David Fernandez (bardo). This has some elements from Civ3, and is
   also designed to reduce the gap between inexperienced and optimal play,
   and for the AI to play well. It is suitable for single-player and
   multiplayer games. See doc/README.ruleset_civ2civ3 for more
   information. GNAPATCH#3366
     * This version of the ruleset is similar to previous versions
       available as modpacks, but does have some changes, including taking
       advantage of new facilities in the game engine. civ2civ3 or civ2_3
       games started in previous versions of Freeciv cannot be continued
       with this version.
     * civ2civ3 is planned to become the default ruleset in a future
       release. The current default ruleset has been renamed to 'classic'
       and will continue to be available. From now on the name 'default'
       will refer to whatever ruleset the running version of Freeciv
       defaults to. GNAPATCH#3216

   Rules changes affecting all or most rulesets:
     * (not civ1/civ2) City tiles are no longer an exception to the rule
       that the 'Bridge Building' technology is required to build roads
       over rivers. Cities on river tiles no longer automatically get
       roads until the technology is acquired. GNAPATCH#3007
     * (not civ2/multiplayer) Cities suffer random disasters such as loss
       of population or buildings. A new server setting 'disasters'
       controls their frequency, or disables them entirely.
     * (not civ1/civ2) 'Barracks' buildings and 'Sun Tzu's War Academy'
       are now cumulative: if you have both, new units are created at the
       Hardened veteran level. GNAPATCH#3062
     * Bombarder units (such as bombers and helicopters in civ2civ3) no
       longer gain veterancy from bombardment. GNAPATCH#5835
     * The maximum number of trade routes per city is now
       ruleset-dependent. In the classic and (of as RC1) experimental
       rulesets, the limit on trade routes now depends on what technology
       you have. You start with 2 per city, and can add one more with each
       of 'Magnetism' and 'The Corporation'.
     * In rulesets with nationality tracking (classic, experimental,
       civ2civ3):
          + Citizens now gradually convert to the nationality of the city
            owner over time, at a ruleset-defined rate. GNAPATCH#2365
          + Units now have their own nationality, which remains the same
            even if they are bribed or captured. Settler units add
            citizens of their own nationality when founding or adding to
            cities. GNAPATCH#3625 GNAPATCH#3635
     * Changes to what happens if research points go negative (due to
       transfer costs or tech upkeep):
          + A new server setting 'techlossforgiveness' controls whether
            technologies can be lost at all, and if so, how much debt
            triggers tech loss. Previously this was controlled by the
            ruleset; of the supplied rulesets, only the experimental
            ruleset had this behavior. GNAPATCH#3193
          + When technology is lost, half the bulb cost of the lost
            technology is now added on to the current bulb balance (this
            may not be sufficient to make it positive). The proportion is
            controlled by the new server setting 'techlossrestore'. The
            old behavior, where any bulb debt was completely cancelled,
            can be restored by setting this to -1. GNA#21623
     * A tile with both a river and a fortress now has a lower defensive
       bonus, as the bonuses are now added rather than multiplied.
     * When a freshwater terrain (lake) and an oceanic terrain type become
       adjacent due to terrain change, the ocean now floods the whole
       lake. GNAPATCH#3478 In rulesets with lakes, transforming a swamp
       bordering a lake now results in lake, not ocean. GNA#20043
     * In games where 'startunits' includes a k)ing unit, such units are
       also given to new players created as a result of civil war.
       GNAPATCH#3812

   Rule changes to specific rulesets:
     * classic:
          + Tracking of citizen nationality is now enabled. See the help
            for what this means. GNAPATCH#3624
     * experimental:
          + New road type 'Maglev', requiring 'Superconductors' and giving
            unlimited movement to 'Land' units. Regular railroads now give
            fast but limited movement (each tile takes 1/9 of a movement
            point). GNAPATCH#3295 GNAPATCH#4008
          + Citizens of your enemies in your own cities cause unhappiness,
            with the amount depending on your government type.
            GNAPATCH#3628
          + Partisan appearance now depends on how many of the conquered
            city's citizens had the nationality of the defeated player,
            rather than the original city owner. GNAPATCH#3762
          + Paratroopers can now paradrop directly to a transport in the
            ocean. GNAPATCH#3805
          + (as of RC1) Caravans are no longer obsoleted by Freight, since
            they can travel on more terrain. GNAPATCH#5791
          + Most technologies now have 'root_req' requirements, preventing
            acquisition of the technology by any means (such as trading)
            unless some key earlier technology is known.
          + By default, it is possible to sustain a small research point
            debt without losing a technology. However, if a technology is
            lost, the debt may not be completely cancelled.
     * civ1 and civ2 (to improve their fidelity):
          + Maximum number of trade routes per city reduced from 4 to 3.
          + When a free tech is granted, it's now chosen randomly, rather
            than being whatever the player was researching.

   New game options:
     * 'killstack', which controls whether all units on a tile die
       simultaneously, is now a server setting (previously it was
       controlled by the ruleset). GNA#18698
     * 'killcitizen' is now a boolean setting rather than a bitfield;
       exactly which units can reduce city population is now controlled by
       the ruleset. GNAPATCH#3613
     * Two new values for the 'diplomacy' setting: "NOAI" which allows
       diplomacy except between AIs, and "NOMIXED" which only prevents
       human/AI diplomacy. GNAPATCH#4213
     * A new setting 'startcity' causes players to start with their first
       city already founded. GNAPATCH#3495
     * (as of beta2) New map generation features ported from warserver: a
       'fair' island map generator ('generator=fair'), which creates an
       identical island for each player or team, and 'teamplacement',
       allowing control of whether team-mates start near each other on the
       map. GNAPATCH#5146 GNAPATCH#5145

   Other changes:
     * Nations:
          + Added 16 new playable nations to standard rulesets, bringing
            the total to 555.
          + The set of 50 'core' nations introduced in 2.4 are now by
            default the only nations that will appear in games. To play
            with the full ('extended') set of nations (which might not be
            translated into your language), change the nation set in the
            'pick nation' dialog, or with the server 'nationset' option.
            GNAPATCH#3448
          + The pirate and barbarian flags be swapped, so that pirates now
            have the Jolly Roger, as they should. GNA#22236
     * In the classic and civ2civ3 rulesets, maps are now generated with
       scenic tile labels on a few random tiles. These have no effect on
       gameplay. GNAPATCH#3147
     * Minor changes to transport units:
          + Units may now load onto and unload from transports that are
            themselves inside another transport. GNA#22050 GNA#22190
          + While there is still no way to choose which transport is used
            if there are several on a tile, cargo units will now prefer
            the transport with more move points. GNA#22189
     * Goto / pathfinding:
          + You can now set waypoints for groups of units starting on
            different tiles. GNAPATCH#4418
          + Improved route planning across 'pontoon bridges' (units
            bridging water). GNA#21871
          + Multiple units working on overlapping connect-with-road or
            similar projects no longer interrupt each other's work.
            GNAPATCH#2206

Changes affecting other rulesets / modders

   Ruleset authors can control much more of the game behavior. Existing
   rulesets need changes to work with 2.5; see
   <http://www.freeciv.org/wiki/How_to_update_a_ruleset_from_2.4_to_2.5>
   for a minimal recipe, and comments in supplied ruleset files for
   documentation and usage examples of new features.
     * Movement
          + Rulesets can now define new types of paths, replacing
            hard-coded road, railroad, and river behavior. Up to 8
            distinct road and/or river types can be defined. Many
            previously hardcoded behaviors are now configurable.
            GNAPATCH#2521
          + Granularity of movement points ('move_fragments') is now
            specified by the ruleset, rather than being hardcoded at 1/3.
            Move rate of 'IgTer' units is also configurable. GNAPATCH#3990
          + The 'Relaxed' orthogonal move mode for rivers (now also
            available for roads) no longer gives a movement bonus for
            diagonal moves unless the path actually links the two tiles.
            GNA#20472
          + Rulesets can allow units to paradrop directly onto transport
            units. GNAPATCH#3805
          + Rulesets have more control over when units can enter and leave
            'unreachable' transports (usually air transports). By default,
            cargo of such transports can no longer embark/disembark unless
            in a city or a base native to the transport, but exceptions
            can be made for individual units. GNAPATCH#3804
          + The game now enforces that no transport unit may contain a
            unit which could transport it, and that units can be nested no
            more than six deep, even if the ruleset would allow these
            situations. This may simplify defining complex transport
            relations in rulesets without defining many unit classes.
            GNA#22050
            (Some versions of 2.4.x had attempts to enforce this, but they
            merely caused error messages rather than preventing the
            situation from occurring.)
     * Terrain and alterations
          + More flexible bases:
               o Rulesets can now define bases which are allowed on city
                 tiles, or automatically added to cities. GNAPATCH#3826
               o Ability and time to build bases can now be
                 terrain-dependent. GNAPATCH#3152
               o Owned bases can now display their owner's flag.
                 GNAPATCH#3450
          + Rulesets can now use effects to change when any of the
            built-in terrain alterations and transformations can be
            performed by units (in 2.4, it was only possible to affect
            irrigation). The full set is:
               o Irrig_Possible: is building irrigation possible?
               o Mining_Possible: is building a mine possible?
               o Irrig_TF_Possible: is changing terrain type with
                 "irrigation" action possible?
               o Mining_TF_Possible: is changing terrain type with "mine"
                 action possible?
               o Transform_Possible: is "transform" action possible?
          + Terrains can now be marked with the 'NotGenerated' flag, so
            that the map generator will not use them (for use in
            scenarios, etc). GNAPATCH#4158
     * Units
          + The unit 'convert' action is no longer instant; it takes a
            ruleset-defined time (at least one turn) for suitable units to
            convert into another type. GNAPATCH#3110
          + The 'Veteran_Build' effect (used for 'Barracks', etc) can now
            cause units to gain multiple veteran levels. GNAPATCH#3062
          + Rulesets are now permitted to contain no city-founding units.
            GNAPATCH#3352
     * Combat
          + Added a general framework for combat value modification based
            on unit type. The old hardcoded 'AEGIS', 'AirUnit', 'Horse',
            'Pikemen', 'Helicopter', and 'Fighter' flags are gone; it's
            now possible to add similar bonuses with different numeric
            values, and more of them. GNAPATCH#3548
          + Whether conquering units reduce city population is now defined
            by the ruleset, per unit class ('KillCitizen'). GNAPATCH#3613
          + Units defending while on non-native terrain (that is, ships in
            harbor) can have a defense penalty applied in this situation,
            via the unit class flag 'non_native_def_pct'. (This is
            distinct from the existing 'BadCityDefender' unit flag, which
            affects firepower.) GNA#20544
          + Sea units' ability to attack neighboring land is generalized
            as ability to attack non-native terrain, and controllable at
            unit class and type level ('AttackNonNative' and
            'Only_Native_Attack' respectively). GNAPATCH#3264
          + Sea units' ability to attack from harbor is generalized as
            unit class ability to attack from city or transport in
            non-native terrain ('AttFromNonNative'). GNAPATCH#3333
     * Cities
          + Cities can suffer ruleset-defined random disasters, whose
            effects can be mediated by the requirements system, and whose
            effects can be implemented by Lua script.
          + The limit on trade routes per city can now vary during
            gameplay (up to a maximum of 5). GNAPATCH#3178 Bonuses,
            ability to establish based on whether route is international
            and/or intercontinental, and what happens if a trade route
            becomes invalid are all now ruleset configurable.
            GNAPATCH#3444
          + As well as the changes to nationality listed in the gameplay
            section:
               o Rulesets can use the "Nationality" requirement in effects
                 to test whether cities contain citizens of a specific
                 nationality. GNAPATCH#3623
               o Rulesets can control whether and how much enemy citizens
                 cause unhappiness with the "Enemy_Citizen_Unhappy_Pct"
                 effect. GNAPATCH#3684
               o Rulesets can choose whether partisan appearance depends
                 on the original city owner or the current nationality of
                 the citizens, and if so what proportion is required for
                 partisans. GNAPATCH#3762
          + The 'Inspire_Partisans' effect can now depend on properties of
            a specific city, not just player-wide requirements.
            GNAPATCH#3763
          + Specialists can now define a fallback graphics tag, so that
            rulesets with custom specialists can be played without tileset
            support. GNAPATCH#4239
          + The image to display for a city (City_Image) is now calculated
            on the server side, allowing ruleset authors to use
            requirements for it that the client may not have reliable
            access to. GNA#19952
          + The way city size is converted into a (cosmetic) population
            number is now more configurable. GNAPATCH#3406
     * Technology
          + New effect 'Not_Tech_Source' prevents players from having
            technology stolen from them. GNAPATCH#3546
          + When a player gets a free technology, the method used to
            choose it is defined in the ruleset in 'free_tech_method'.
            Instead of the previous behavior of giving the player their
            currently researched technology, the ruleset can now specify
            the cheapest or a random technology. GNAPATCH#3552
            GNAPATCH#3553
          + New tech_upkeep_style 'Cities', where tech upkeep scales with
            number of cities.
          + A player will no longer lose a technology (due to tech upkeep,
            etc) if it's a root_req for another technology the player
            knows. GNA#19176
          + The ruleset can request that technology help be popped up in
            the client when a new technology is acquired, via
            'popup_tech_help'. (This can be overridden by the user.)
            GNAPATCH#3480
     * Nations
          + Nations can have an associated color; if the server setting
            'plrcolormode' is set to the new value 'NATION_ORDER',
            players' colors will depend on their nation. GNAPATCH#3443
          + Rulesets can now define playable subsets of their nations
            ('nation sets'), one of which can be picked by players during
            game setup. This could be used for instance to define a number
            of different balanced sets of nations which have unique
            traits, perhaps tailored to different numbers of players.
            GNAPATCH#3448
          + The list of supplied nations has been split out to a new
            'nationlist.ruleset', so that rulesets can use these nations
            while changing other aspects of 'nations.ruleset'.
            nationlist.ruleset has its own lists of governments, terrains,
            etc, so that it can be used by rulesets that are slightly
            different without errors.
     * Effects and requirements
          + 'Resource' added as requirement to effects system.
            GNAPATCH#3322
          + City effects can now depend on the presence of terrain with
            certain properties within the city's workable radius, by
            specifying 'Terrain', 'Resource', etc with 'City' range.
            GNAPATCH#3740
          + City effects can now place requirements on the city's own
            tile. GNA#19874
          + Expanded the ability to group ruleset objects into sets for
            requirement purposes with custom flags:
               o Terrains and technologies now have custom flags, as well
                 as units, enabling limited disjunctive ("or") requirement
                 definitions for these types. GNAPATCH#3487 GNAPATCH#4074
               o Requirements can test these flags. GNAPATCH#3395
                 GNAPATCH#4069
               o User flags now have ruleset-defined help text.
               o The maximum number of user flags for unit types has
                 increased from 4 to 16 (as these are used for the combat
                 bonuses framework). GNAPATCH#3393
          + For boolean effects, negative values are now evaluated as
            'false', to ease ruleset development. GNAPATCH#3396
     * Lua scripting
          + Updated scripting engine to Lua 5.2. GNAPATCH#3230
          + Scripts can now set tile labels. GNAPATCH#3136
          + Scripts can now run on a new 'map_generated' signal.
            GNAPATCH#3135
     * Misc
          + It's now possible to have multiple centers of government for
            the purposes of calculating waste and corruption, through the
            'Gov_Center' effect. The distance to the nearest determines
            waste. GNAPATCH#3342
          + When a 'GameLoss' unit is killed, instead of the player's
            assets (units, cities, etc) just disappearing, the ruleset can
            cause some of them to be transferred to the conqueror,
            barbarians, and/or a new AI player ('gameloss_style').
            GNA#20577
          + Rulesets can specify that start positions must be surrounded
            by a minimum area whose terrain is native to starting units
            ('min_start_native_area'). GNAPATCH#3614
          + Rulesets can completely disable civil war
            ('civil_war_enabled'). GNAPATCH#3818
          + Technologies with the 'Claim_Ocean' flag lift the normal
            restrictions on borders claiming ocean tiles. GNAPATCH#3355
          + The ruleset can define a 'preferred_soundset' which will be
            suggested to clients. (Only Gtk2/3 clients can ask the user;
            with other clients the user has to have enabled auto-accept
            for this to take effect.) GNAPATCH#3226

   Tileset authors have a few new facilities. Existing tilesets need
   changes to work with 2.5 at all; see
   <http://www.freeciv.org/wiki/How_to_update_a_tileset_from_2.4_to_2.5>
   for a minimal recipe.
     * When a unit is building a base or road, tilesets can now display an
       icon specific to that base/road. GNAPATCH#3305
     * The layer that darkness is drawn at is now configurable
       ('darkness_layer'). GNAPATCH#4461
     * Tilesets can now supply icons for unit upkeep greater than 2 to be
       displayed in the city dialog. GNAPATCH#3824
     * In the supplied tilesets, government and specialist icons have been
       split to separate files, so custom tilesets can replace them while
       continuing to use other graphics from the standard small.spec.
       GNAPATCH#4076 GNAPATCH#4422

   Scenario creators have a couple of new features available. (Scenarios
   created with previous versions should continue to work in 2.5.)
     * Most of the supplied rulesets now include an 'Inaccessible' terrain
       type, for use by scenario authors to shape the map area. See the
       France scenario for an example of its use. GNAPATCH#4159
       GNAPATCH#4158
     * Scenarios can now restrict the set of available nations (to those
       with start positions). GNA#21268

Changes affecting server operators

     * Failure to load a ruleset no longer causes the server to quit; it
       now reverts to the previously loaded ruleset, or failing that the
       default ruleset. GNAPATCH#1449
     * On Windows, the server no longer sets the socket option
       SO_REUSEADDR on its listening socket. This may fix some issues with
       clients connecting to the wrong server. GNA#21583
     * The default database backend for authentication has changed from
       MySQL to SQLite. GNA#19909
     * There's no longer support for attempting to save games in formats
       compatible with previous major releases of Freeciv. The
       'saveversion' server option has been removed. GNAPATCH#3188
       GNAPATCH#3026

AI

   There have been some improvements to the standard AI's behavior:
     * Defense
          + Autosettlers are smarter about spotting danger: GNAPATCH#3854
               o Sea and air units are now considered threats, not just
                 land units.
               o Military units which can't attack are no longer
                 considered threats.
          + Cities needing defense are less prone to building walls before
            units. GNAPATCH#4798
          + The AI now considers non-land units that can conquer cities
            (such as Helicopters) a threat to continents it controls.
            GNA#22225
          + The AI should more correctly account for travel time when
            assessing danger to cities from enemy units; previously it
            treated them as its own, which could be wrong for ZoC,
            restrictinfra etc. GNAPATCH#3729
          + (as of RC1) The city the AI has nominated to build wonders is
            now permitted to build defensive units instead if necessary.
            GNAPATCH#5588
          + (as of RC1) The AI now treats players it has never met as
            potentially hostile; this should make it harder for human
            players to sneak forces into place before first diplomatic
            contact. GNAPATCH#5441
     * Unit handling
          + Some fixes to AI's handling of boats as transports.
     * Terrain improvement
          + The AI and autosettlers' relative weightings have been tweaked
            to give slightly better behavior with typical rulesets. In
            particular, production is now valued less compared to other
            outputs. GNAPATCH#3692
          + The AI and autosettlers can now decide to build bases, if they
            provide any direct output bonus to a nearby city, or enable
            another base which does so. (Bases are still not built for
            purely strategic purposes.) GNAPATCH#3341 GNAPATCH#3833
     * Economy
          + When the AI is on a war footing, it now prefers diverting
            taxes to science rather than luxury. GNA#21640
          + The AI now considers keeping units in cities for their martial
            law effect, although it will not yet build units specially for
            this. GNAPATCH#3959
          + The AI values coinage less, to balance it compared to
            gold-producing buildings. GNA#21796
          + The AI may now create trade routes between continents.
            GNAPATCH#2963
     * Research
          + The AI now considers more combat bonuses when deciding what
            technology to research. For instance, it may now work harder
            towards AEGIS Cruiser when defending against air units.
            GNAPATCH#3555 GNAPATCH#3563
          + The AI no longer chases technologies to gain units that are
            already obsolete. GNAPATCH#4013
          + The AI no longer remembers its past desire for long-obsolete
            technologies indefinitely. GNA#22260
     * Ruleset tolerance
          + In rulesets which support ocean cities, the AI now considers
            building them. GNAPATCH#3533
          + The AI no longer builds sea-only worker units if the ruleset
            has them. This is a temporary solution to a previous issue
            where AI would build only sea worker units when they became
            available, and not land ones. GNAPATCH#4610

   AI behavior is also now somewhat more configurable by rulesets:
     * The new traits framework allows AI behavior to be parameterized
       (current traits are Expansionist/Trader/Aggressive). Traits can be
       set in rulesets (globally or for specific nations), or by Lua
       script. GNAPATCH#3001
     * The 'Cheating' level AI no longer intrinsically ignores tax rate
       limitations. This is instead left up to the ruleset. The supplied
       rulesets give cheating AIs this bonus, so there is no functional
       change. GNA#18232

   The following changes are only relevant to AI developers:
     * 'Default' AI logic, which was previously tied to the 'classic' AI
       type, can now be used selectively by custom AI modules, each with
       their own instance data.
     * The default AI type can be chosen at configure time. GNAPATCH#3666
     * Some progress has been made on the 'threaded' AI variant. It is now
       functional, but does not yet offer much advantage over the
       'classic' AI. The only difference is that cities can make specific
       requests of worker units. The 'threaded' AI is not included in
       standard builds.

Clients

     * (as of beta2) The Qt client is now substantially complete, and a
       Windows build is available. A Qt version of the modpack installer
       is also available.
     * The city map size in the city dialog now adapts to the ruleset.
       This means that the city dialog in the SDL client is no longer
       unusably small with the classic and similar rulesets. GNAPATCH#4389
     * The client now only lists scenarios for "Start Scenario Game";
       previously it could include ordinary save files that happened to be
       on the scenario path. GNA#22209
     * Client options to control whether tileset and soundset suggestions
       made by the ruleset are automatically accepted. This allows clients
       other than the Gtk clients to make use of these suggestions.
       GNAPATCH#3599 GNAPATCH#3605
     * (Gtk) The pregame nation selection dialog has been rewritten,
       fixing many small bugs. GNAPATCH#4347
     * (Gtk) The client can now optionally pop up help for a new
       technology when it's acquired. GNAPATCH#3608

Modpack installer

     * The modpack installer now keeps track of versions of packages it
       has previously installed. (It does not track changes made
       manually.) GNAPATCH#3163
     * A command-line tool for downloading modpacks, freeciv-mp-cli, has
       been created for use on headless servers. GNAPATCH#4436
     * The modpack installer can be built into multiple GUI flavored
       executables simultaneously. As a result, the executables have been
       renamed.
     * Modpacks can now have descriptions GNAPATCH#3645 and a 'subtype'
       field (e.g. to distinguish iso/hex tilesets) GNAPATCH#4394.

Tilesets / Art

     * The activity icons shown near units building roads and bases in
       Cimpletoon, Amplio2, and Trident are now small versions of the
       extras themselves. GNAPATCH#4059 GNA#20032 GNAPATCH#5856
     * (as of RC2) The Trident tileset has been updated for various
       recently added game elements, including lake and maglev.
       GNAPATCH#5856 GNAPATCH#5877
     * Improve colors for global warming / nuclear winter progress
       indicators. GNAPATCH#4827
     * The icons for entertainers, scientists, and tax collectors now have
       both male and female versions. GNAPATCH#4506
     * Made a few specialist icons available for custom rulesets (worker,
       farmer, merchant) for use by modpacks. These are not used in the
       supplied rulesets. GNAPATCH#4467
     * The Cimpletoon and Amplio2 (as of RC1) and Trident (as of RC2)
       tilesets have 'outpost' and 'airstrip' graphics for use by
       modpacks. GNAPATCH#5027

Translations

     * Updated French, Polish, Catalan, Russian, Korean, Scottish Gaelic,
       British English, traditional Chinese, Spanish, German, Japanese,
       Finnish, and Irish localizations.

Build/portability

     * A real thread implementation is now a hard requirement.
       GNAPATCH#2996
     * The SDL client now requires SDL_gfx and SDL_ttf libraries. Copies
       are no longer included with the Freeciv source. GNAPATCH#4088
       GNAPATCH#4386
     * Clients other than the SDL client can now be built against
       SDL2_mixer. GNAPATCH#4189
     * (as of beta2) The build is now Clang-clean (with 3.3, 3.4, and
       3.5).

   See doc/README.packaging for more information.


MAJOR CHANGES FROM 2.3.x to 2.4.0
---------------------------------

   (from <http://www.freeciv.org/wiki/NEWS-2.4.0>, 2013-09-14)

   As is usual for major releases, 2.4 clients cannot interoperate with
   pre-2.4 servers, and vice versa. Pre-2.4 savegames can however be
   loaded into 2.4, and in most cases, the supplied rulesets have not
   changed so much as to make it difficult to complete a game started with
   2.3.x's rules.

Server / General

Gameplay

     * The maximum theoretical map size has increased from 128,000 to
       2,048,000 tiles; the maximum linear map dimension has increased
       from 512 to 32,768. GNA#18087
     * If map generation fails (for instance the common failure to
       allocate start positions), it is now retried with a different
       random seed. GNAPATCH#2402
     * A couple of new server settings have been added to customise
       gameplay:
          + 'revealmap' allows the map to be shown to all players at game
            start, or to dead players. GNAPATCH#2379
          + 'first_timeout' allows the first turn to have a different
            timeout from subsequent turns. GNAPATCH#1967

Clerical

     * Player authentication has been revamped. Database access is now
       mediated by a Lua script that can be customised by server
       operators, and uses Luasql, enabling a variety of backends: MySQL
       (the only backend supported previously), SQLite, and PostgreSQL.
       See doc/README.fcdb for details. GNA#13643
          + Support is included 'out of the box' for SQLite and MySQL
            databases. SQLite uses a simple file as a database, and is
            recommended as being entirely adequate for Freeciv
            authentication and much less hassle to set up than MySQL.
          + The Windows packages include SQLite support, so for the first
            time, it's possible to use player authentication on Windows
            without building the server yourself.
     * The server now supports a 'delegation' feature similar to that in
       Longturn, where one user can nominate another to temporarily take
       over control of the game. This is controlled by the '/delegate'
       server command. GNAPATCH#2121
     * There is a new "map image" feature to save an overview map as an
       image. This is a much expanded version of the previous --Ppm server
       feature, which has been removed. Compared to --Ppm, the new feature
       can distinguish units, cities, borders, terrain colors, hex tiles,
       and more. Saving images can be triggered automatically (turn-based)
       on the server, or on demand on the server or client. See the
       '/mapimg' server command. GNAPATCH#1391
          + A series of these images can be assembled into an animation to
            replay the progress of the game. A shell script 'mapimg2anim'
            is provided to help with this.
          + PNG/GIF/JPEG output is only available if built against the
            ImageMagick library; this is included in the Windows packages
            as of 2.4.0-RC1.
     * Player colors are now assigned centrally, and can be changed with
       the '/playercolor' server command. There is a new server setting
       'plrcolormode' that controls how colors are assigned, including a
       mode where all players on a team have the same color. GNAPATCH#2062
          + The set of default player colors in the supplied rulesets has
            been reworked to enhance visibility of borders against
            terrain, etc. GNA#19778
     * The colors used to represent different terrain types on the minimap
       have been reworked. GNAPATCH#2069
     * The 'autosaves' setting gives finer control over when savegames are
       generated. GNAPATCH#2536
          + To disable autosaves entirely, instead of '/set saveturns 0',
            it's now necessary to use a command like '/set autosaves ""'.
     * The scripts 'ser' and 'civ' have been renamed to 'fcser' and
       'fcgui' respectively. GNAPATCH#2830
     * A Lua script can be read from a file with the '/lua file' command.
       Direct Lua input is now via the '/lua cmd' command. GNAPATCH#2338
       GNAPATCH#2869
     * New server option --Bind-meta to control which network interface
       the metaserver connection is made from. GNA#14106
     * The server can be built with support for .xz (LZMA) compression for
       saved games, etc. See the 'compresstype' option. GNAPATCH#1810
     * The freeciv-modpack utility supports more modpack types, more
       options (see --help), and uses the Curl library for network access
       so should be more robust.
     * (as of beta2) The ranklog format has changed; it now includes
       individual players' scores, and can be parsed more unambiguously.
       GNAPATCH#3346

Clients

     * There is a new client, freeciv-gtk3, based on version 3 of the Gtk+
       toolkit. This is fully playable and has largely identical UI and
       functionality to freeciv-gtk2. Currently it is experimental;
       however, it is expected that it will become the default client in
       the next major release.
          + The first time you run this client, it will copy any Gtk2
            client settings you have set. Thereafter, Gtk2 and Gtk3
            settings will remain separate.
          + Known issue in beta1/beta2: when compiled against some
            versions of Gtk3, there are assertion failures and crashes
            associated with the unit selection dialog. This is believed
            due to a Gtk bug (671939); however, it's been worked around in
            the Freeciv code as of RC1. GNA#19846
     * (In the code there is also the start of a Qt client. However, at
       this point it is just a stub and is unlikely to be of interest.
       Development will continue in 2.5.)
     * A server spawned by the client now only listens on the local
       network interface, so clients on other machines cannot connect to
       it. This improves security for single-player games, but means that
       a multiplayer game can no longer be hosted by the client; you must
       start a separate server instead (see the FAQ). GNA#18530
     * It's now possible to display a map overlay indicating which tiles
       the currently selected unit can enter ("native" tiles), with the
       Shift-Ctrl-N keyboard shortcut. GNA#13620
     * The research speed in bulbs per turn is now available with other
       research information from popups/tooltips on the main window.
       GNA#17685 GNA#16481
     * For rulesets where different nations have unique gameplay
       attributes (different initial governments, techs, units, or
       buildings), this information is now available when picking a nation
       in the pregame, and in the online help. GNAPATCH#3066
     * The client now displays the current stable version of Freeciv and
       whether that's newer than the running version (this information
       comes from the metaserver). GNAPATCH#2735
     * (Gtk) The client now has a Lua scripting console. GNAPATCH#2515
          + This is currently something of a proof of concept rather than
            a finished feature, as a comprehensive API suitable for the
            client-side has not been provided. Notably, there are not yet
            any signals from which client-side scripts can be triggered.
          + However, client scripts do have access to the client's view of
            most of the same game data that server-side ruleset scripts do
            (map, units, cities etc); see the Lua reference manual. This
            should be sufficient for some useful work. For example, it
            should in principle be possible to implement an on-demand
            optimal trade route calculator with these facilities (although
            we haven't tried).
     * (Gtk) The unit selection dialog has been revamped to allow browsing
       and selecting units by combinations of location and activity,
       anywhere in the world. GNA#17236
     * (Gtk) A bribe cost is now shown in the popup for units (for enemy
       units, this is estimated). GNA#17489

Tilesets / Art

     * The orientation of units is now tracked, so tilesets can provide
       different graphics for different unit orientations. GNAPATCH#2719
          + A tileset making use of this, Cimpletoon, is included. It is
            based on Amplio2 but has a full set of oriented unit sprites
            for the default ruleset. GNAPATCH#2739
          + Known issue in beta1: Cimpletoon did not have sprites for all
            Fundamentalist units (it lacked Elephants and Crusaders), so
            for rulesets with these units, it would use fallback sprites
            (Chariot and Knights respectively). As of beta2, the tileset
            is complete. GNA#19998

Gameplay / Rules

Changes affecting supplied rulesets

     * Nations:
          + The number of playable nations has increased from 385 to 539.
          + Out of these, a subset of 50 "core" nations has been defined,
            based mostly on nations that have appeared in the Civilization
            series of games. For localised versions of Freeciv, these
            nations are more likely to be translated than the remainder.
            Players are initially presented with the core set, and it will
            be used for random nation selection if no nations are
            specifically selected; but players can still select nations
            outside the core set, and if some do, then the full range of
            supplied nations will be used for random selection of
            remaining players. GNAPATCH#3449 GNAPATCH#3432
          + The civ1 and civ2 rulesets now have their own separate nation
            sets, more closely matching the original games. GNAPATCH#2243
     * City center tiles now lose their automatic irrigation bonus if a
       mine is built on them, since mines and irrigation cannot coexist on
       a tile. GNA#20932
          + Similarly, in the supplied rulesets, cities on a tile with a
            mine can no longer get a farmland bonus.
     * The effect of veterancy on the cost of bribing a unit now depends
       on veteran bonuses, not numeric veteran level; bribe costs for
       veteran units have thus changed. GNA#19253
     * When the 'barbarians' server setting is disabled, huts no longer
       spawn barbarians.
     * When migration is enabled, citizens now consider the risk of plague
       when deciding whether to migrate. GNA#17740
     * In rulesets without tech upkeep enabled, if the bulb count goes
       negative (for instance due to 'conquercost'), technologies are no
       longer lost. This restores the behavior of previous versions of
       Freeciv. GNA#19487
     * Diplomats and Spies now have special names for their veteran
       levels, but behavior is unchanged from 2.3. GNA#19850
     * In the default, multiplayer, and experimental rulesets, years are
       displayed with CE/BCE rather than BC/AD notation. GNA#15090
     * (as of beta2) The default map topology for new games has been
       changed to isometric, to match the default Amplio2 tileset.
       GNAPATCH#3764
     * (as of beta2) In the 'multiplayer' ruleset, the ability to build
       buoys has been removed, as they do not work well with national
       borders disabled (the default for this ruleset). It is expected
       that they'll be re-enabled in a future major release. GNAPATCH#3541
     * Changes to the 'experimental' ruleset:
          + Citizen nationality is enabled; see below.
          + Workers and Engineers can now gain veteran levels by working
            the land; this in turn allows them to work faster.
            GNAPATCH#2370 GNA#19818
          + A Mech. Inf. unit can now carry up to three Missile units.
            GNAPATCH#2481
          + Galleons can now carry Big Land units, and Frigates no longer
            can. Old savegames are handled gracefully. GNAPATCH#2643

Changes and new features for rulesets/modpacks/scenarios

     * New feature: optionally, the nationality of citizens can be
       tracked. For instance, when you conquer a city, its citizens retain
       their original nationality. Currently this affects the cost of
       inciting cities and the chance of migration (if enabled); more
       effects are planned for future versions. GNAPATCH#2265
     * The veteran system has been reworked:
          + Per-unit veteran levels have been generalised; all veteran
            properties can now be set on a per-unit basis; previously, the
            chances of moving between levels could not. This means that
            different units can now usefully have different numbers of
            veteran levels for the first time. GNAPATCH#2346
          + Diplomatic combat and spy mission survival chances are now
            derived directly from the 'power_fact' property of the veteran
            level, rather than being based purely on the numeric veteran
            level. GNA#19850
          + As noted above, the effect of veterancy on unit bribe costs
            has changed.
          + The maximum number of veteran levels has doubled from 10 to
            20.
          + Units with only a single veteran level, or which can't become
            veteran, now do not have a veteran level displayed.
          + Information about veteran levels is now included in the
            on-line help. GNA#19851
     * Recursive transports are now supported (up to a depth of 5).
       GNAPATCH#2270
     * Two new tech_cost_styles: 3 with a new formula (early techs
       slightly easier, later techs much harder), and 4 which is similar
       to 2 (read from ruleset) but with the gaps filled with the new
       formula. GNAPATCH#2396
     * A new effect 'Irrig_Possible' and requirement range 'CAdjacent'
       (cardinally adjacent) have been added. The requirement for oceans
       or rivers for irrigation is thus no longer hardcoded and can be
       modified. GNAPATCH#2450
     * The 'CityTile' requirement now supports 'Adjacent' and 'CAdjacent'
       ranges, so effects can be triggered for tiles next to a city.
       GNA#18551
     * 'Surviving' requirements for wonders are now supported at Player
       range as well as at World range. GNA#17463
     * In ruleset definitions, specifying 'move_type' for a unit is now
       optional; if not specified it will be inferred from the native
       terrains/specials of the unit. GNA#13630 GNAPATCH#2991
     * A ruleset can now specify a 'default_government' for all its
       nations in nations.ruleset, rather than each nation being required
       to specify its initial government individually. GNAPATCH#3031
          + The supplied nations no longer include
            init_government="Despotism", so they can be used in rulesets
            which require a different initial government. GNAPATCH#3032
     * The image used for a city in the client is now set by the effects
       system (effect 'City_Image'), so it's no longer constrained to be a
       simple function of city size. GNA#17110
          + The experimental ruleset uses this to align city graphics with
            the city map radius.
     * Tile labels are supported. These are text labels that are displayed
       by all clients when they display a particular map tile. They can be
       added to scenarios in the editor. GNAPATCH#2408
     * The colors used for players, and for terrains on the minimap and
       map images, are now specified by the ruleset on the server side,
       rather than the tileset on the client side. GNAPATCH#2060
       GNAPATCH#2061
     * In rulesets with tech_leakage enabled, dead players are no longer
       taken into account in the calculation; so you cannot gain from
       their knowledge, but equally a dead, ignorant player no longer
       pushes up research costs. GNAPATCH#2956
     * The behavior where the senate of representative governments is
       bypassed has moved from the Any_Government to the No_Anarchy
       effect. GNA#19107
     * The 'min_dist_bw_cities' ruleset item has been retired; use the
       'citymindist' option instead. GNAPATCH#2537
     * Many changes to ruleset Lua scripting -- for full details see the
       Lua reference manual. These are all backward compatible.
       Highlights:
          + Script-triggered climate change (GNAPATCH#2624) and civil war
            (GNAPATCH#2627).
          + Scripts can now move existing units.
          + A script can test whether tiles have a particular base.
            GNAPATCH#2672
          + Script facilities for reading and manipulating unit
            orientation. GNAPATCH#2823 GNAPATCH#2836
          + Scripts can now read server settings. GNAPATCH#2955
     * (as of beta2) An internal 64kbyte limit on string length has been
       removed. Among other things, this allows longer Lua scripts in
       scenarios. GNA#20086

AI

     * (as of beta2) The city governor logic has been reworked, fixing
       various issues such as unexpected tax collectors in cities with
       many buildings, and a need to set minimal gold surplus to a lower
       target than expected. GNAPATCH#3620
     * (as of beta2) The AI's workers/settlers, and human players'
       autosettlers, will now automatically stop what they are doing and
       go elsewhere if threatened by an enemy unit and there is no
       defender on their tile. (Currently only threats from land units are
       considered.) GNAPATCH#3384
     * (as of beta2) Improvements to AI settler management:
          + The AI now considers worker units' food consumption (e.g.
            Settlers) to be less of a factor when deciding whether to
            build such units, to encourage it to do so. GNAPATCH#3693
          + Fix poor handling of rulesets containing boats which can only
            carry a single unit. Previously, the AI would generate
            settlers with the intention of sending them out on such boats,
            but then refuse to do so due to lack of room for a bodyguard,
            regardless of whether one was needed, often hurting expansion
            and leaving useless settlers. Now it only insists on room for
            a bodyguard if one is actually needed. GNA#19815
     * Improvements to AI city defense:
          + (as of beta2) Reduced the tendency of AI city defenders to be
            lured out of their city by nearby targets even in the presence
            of threats. GNA#20504
          + (as of beta2) Cities in grave danger of invasion with no
            defending units were tending to build City Walls, uselessly.
            They will now prioritise acquiring a defender. GNA#20559
          + (as of RC1) Reduced the weighting of the AI's assessment of
            defence strength, so that it defends its own cities more
            convincingly. (part of GNAPATCH#3960)
          + (as of RC1) The AI now tends to keep a unit constantly
            defending each of its cities even in the absence of an obvious
            threat, rather than relying on being able to acquire one when
            a threat appears. GNAPATCH#3958
     * (as of beta2) Improvements to AI caravan management:
          + Caravans in transit are now taken into account when a city is
            deciding whether to build more caravans. Previously, a city
            could end up building endless caravans if existing ones did
            not complete their trade route. GNAPATCH#3529
     * (as of RC1) The AI's new weighting of defence strength assessment
       means that it is less fearful of its enemy's defenders when
       attacking their cities. (part of GNAPATCH#3960)
     * The AI's management of its tax rates has been reworked to be more
       sophisticated; notably, it now takes tech upkeep into account. It
       also considers tech upkeep when determining the value of a tech.
       GNAPATCH#2251
     * AI planning for new cities has been improved slightly. GNA#19449
     * Autosettler planning for building railroads (GNAPATCH#2885,
       GNA#19560) and farmland (GNAPATCH#2889) has been improved. (Note
       that the latter is still only triggered by the existence of a
       Supermarket, so the AI still does not benefit, due to a
       chicken-and-egg situation.)
     * The extensive reworking of the AI code (see #Development), while
       not intended to introduce any functional changes (and extensively
       tested for this), may have changed behavior in some rare cases.

Translations

     * New Indonesian translation.
     * (as of beta2) New Traditional Chinese translation.
     * Updated translations: Bulgarian, Catalan, Spanish, Scottish Gaelic,
       Korean, Polish, Dutch, Irish, French, German, Finnish, and British
       English.

Development

     * The AI code has been heavily refactored, with a view to making it
       easier for people to start their own projects to write better
       Freeciv AI.
          + There's now a concept of AI type; different players can have
            different AIs. The type can be specified to the server /create
            command and the Lua function edit.create_player().
          + The server can be built to accept dynamically loadable AI
            modules with the --enable-aimodules option to configure. A
            module is loaded by starting the server with the --LoadAI
            option.
          + Alternatively, a fixed set of modules can be compiled in with
            --enable-ai-static.
          + In addition to the 'classic' AI, the standard Freeciv package
            ships with the 'stub' and 'threaded' AIs. These are both dummy
            templates for development and do not work as shipped. They are
            enabled with the configure option
            --enable-aimodules=experimental.
          + See doc/README.AI_modules for some more information.

Build/portability

     * There is now a hard dependency on libcurl for HTTP access. This is
       used for metaserver communication and for freeciv-modpack.
       GNAPATCH#2320 GNAPATCH#2376
     * Efforts have been made to make the codebase compile without
       warnings with GCC 4.6 and (as of beta2) 4.7.
     * Use of some GNU make extensions has been removed from the build
       system, so it may now be possible to build with a POSIX 'make'.
       GNAPATCH#3378
     * freeciv-modpack can be built against either gtk2 or gtk3.
       GNAPATCH#2762
     * The configure option --enable-sys-lua allows use of a system-wide
       copy of Lua instead of the one shipped with Freeciv. GNAPATCH#2747

   See doc/README.packaging for more information.


MAJOR CHANGES FROM 2.2.x to 2.3.0
---------------------------------

   (from <http://www.freeciv.org/wiki/NEWS-2.3.0>, 2011-08-08)

   As well as many new features, many features from Longturn and some from
   Warclient have been merged into the main codebase for this release.

   A new program has been added to the Freeciv suite: 'freeciv-modpack'.
   This makes it easier to download and install add-ons ('modpacks':
   rulesets, tilesets, etc) to the right place; you can enter a URL,
   choose an add-on from the list, and the tool will install it to the
   correct place for this version of Freeciv to use it. Modpack authors
   should see this page for details of how to publish modpacks for
   installation by this program. GNAPATCH#1822

   As is usual for major releases, 2.3 clients cannot interoperate with
   pre-2.3 servers, and vice versa. Pre-2.3 savegames can however be
   loaded into 2.3, and in most cases, the supplied rulesets have not
   changed so much as to make it difficult to complete a game started with
   2.2.x's rules.

Server / General

Gameplay

     * Various limits have been lifted, including:
          + Maximum number of simultaneous players increased from 30 to
            126 GNAPATCH#1731
          + Map size
               o Maximum map size increased from 30,000 to 128,000 tiles;
                 maximum linear map dimensions increased from 254 to 512
                 GNAPATCH#1733
               o Minimum map size reduced to 16x16(!) GNA#17031
          + Allow goto paths that take more than 99 turns GNA#16792
     * There are now more ways of specifying the map size. Instead of
       specifying the size in thousands of tiles (via the 'size' option),
       you can specify the number of tiles per player ('tilesperplayer'),
       or the exact X and Y sizes ('xsize' and 'ysize'). The method is
       selected with the 'mapsize' option. GNAPATCH#1720
     * A number of new server settings have been added to customise
       gameplay:
          + 'killunhomed': units without a home city (such as starting
            units) can be configured to lose hitpoints each turn until
            they die. GNAPATCH#1501
          + 'unreachableprotects' controls whether 'unreachable' units
            (such as Bombers) protect the whole stack on their tile as in
            previous versions. If this is unset, a mixed stack is
            vulnerable to attack (including normally-unreachable units).
            GNAPATCH#1850
          + 'unitwaittime' allows a minimum time to be enforced between
            actions of a given unit on successive turns, to mitigate the
            'double-move problem'. GNAPATCH#1500
          + 'restrictinfra' allows enemy use of infrastructure such as
            roads and rails to be restricted. GNAPATCH#1266
          + 'airliftingstyle' allows airlifts between allied cities, and
            unlimited airlifts per turn. GNAPATCH#1189
          + 'techlost_recv'/'techlost_donor' allow introduction of a risk
            of technology loss when technologies are transferred between
            civilizations (via diplomacy, espionage, conquest etc).
            GNAPATCH#1263
          + 'trading_tech'/'trading_gold'/'trading_city' allow certain
            types of diplomatic agreements to be selectively disabled.
            GNAPATCH#1504, GNAPATCH#1506
          + 'globalwarming'/'nuclearwinter' allow these global
            catastrophes to be disabled. GNAPATCH#1505
          + 'team_pooled_research' allows pooled research to be disabled.
            GNAPATCH#1868
          + 'alliedvictory': all players in an alliance can share victory.
            This new behaviour is enabled by default. GNA#14278
     * (as of rc1) Changes to the 'timeout' setting now always have
       immediate effect, as in 2.0.x; previously, changes between non-zero
       values would not take effect until the next turn. GNA#18079
     * Improvements to observing:
          + The demographic report is now available to global observers.
            GNA#16486
          + Global observers can now view the city report (it shows cities
            from all nations). GNA#16699 GNAPATCH#2571
          + Global observers can now access the buildable target list in
            the city dialog. GNA#16487
     * The number of units built, killed, etc now contributes to the final
       score, and appears in the endgame report. GNAPATCH#1870
     * Changing a unit's activity is now more forgiving: if you
       accidentally stop an activity such as irrigation, but restart it
       without doing anything else, progress is no longer lost. GNA#15510

Clerical

     * Settings configuration on the client and server has been reworked.
       The most notable change is that enumerated and bitwise options are
       now set with strings instead of numbers (for instance, '/set
       barbarians hordes' instead of 4, '/set topology wrapx|wrapy'
       instead of 3). GNAPATCH#1301
     * The FREECIV_PATH environment variable can be overridden by three
       new variables: FREECIV_DATA_PATH, FREECIV_SAVE_PATH, and
       FREECIV_SCENARIO_PATH. GNA#14624
     * Add-ons are now loaded from a sub-path ~/.freeciv/<version>/ (e.g.,
       ~/.freeciv/2.3/), since they tend to be specific to a version of
       Freeciv. GNA#14624
     * Servers send more information to the metaserver:
          + The 'timeout' and 'aifill' options (GNAPATCH#2092);
          + (as of beta2) the number of human players (as opposed to AIs)
            (GNAPATCH#2312); as of beta3 this is displayed in the client
            (GNAPATCH#2411)
     * New server command '/kick' and associated option 'kicktime' to lock
       out troublesome users. GNA#16933
     * New server commands '/ignore', '/unignore', and '/list ignored
       users', allowing players to suppress chat messages from specific
       users. GNAPATCH#1910
     * The '/create' command can now create a new player even in a running
       game. GNAPATCH#1574
     * New command '/lua' to execute a line of Lua script on the server
       command line. GNA#15644
     * More options have been added to the '/reset' command. GNAPATCH#1284
     * The name of the scorelog file is configurable with the new
       'scorefile' option. GNAPATCH#1750
     * The current ruleset can be shown by '/show rulesetdir' instead of
       '/rulesetdir' (this allows less privileged users to do so).
       GNA#16636
     * Observers can see the current votes in progress with the new
       command '/list votes'. GNA#16635
     * The server uses a new format for savegames. It can load savegames
       generated by old versions of Freeciv, but old versions will not be
       able to load new savegames. GNAPATCH#1541
          + Support has been added for future versions of Freeciv to save
            backward-compatible savegames (back to 2.3.0) via the
            'saveversion' server option.

Clients

     * Various report screens have been reworked so as not to redraw and
       lose their selections after a few seconds. GNA#16439
     * The total revenue from trade routes is now visible in the city
       report. GNA#16812
     * The chat log file name is now configurable. GNAPATCH#1749
     * (GTK) Some rework of the pregame connection screen and menus
       (GNA#16685). Buttons on this screen now adapt to selected
       player/user (GNA#15300).
     * (GTK) Tab completion of user and player names on the chatline.
       GNAPATCH#1867
     * (GTK) The goto/airlift dialog now shows which nation each city
       belongs to, and more detail on airlift capacity. GNA#15313
       GNAPATCH#2588
     * The research report is now updated when tax rates or city science
       output change. GNA#16776
     * (as of beta2) Improve handling of (non-default) rulesets which
       restrict reachability of technologies (via root_req in the ruleset)
       in the science report. You can now choose whether unreachable
       technologies are displayed. GNA#16852, GNA#16855, etc
     * (as of beta2) (Xaw) The Take Player command is implemented.
       GNAPATCH#2253
     * (as of rc1) In 2.2.x, the "Sell Obsolete" button in the Economy
       report could never be pressed. It has been renamed to "Sell
       Redundant", and now lets 'redundant' buildings be sold en masse
       (redundant buildings are those whose effects are entirely
       superseded by another, for which you may still be paying upkeep --
       for instance, Power Plants are redundant in cities with a
       Hydro/Nuclear/Solar Plants). In the Gtk client, the "Obsolete"
       column in the Economy report has been replaced with a "Redundant"
       column showing how many of each building in your empire are
       redundant. GNA#17937

Gameplay / Rules

Changes affecting supplied rulesets

     * Two new rulesets are included in the distribution:
          + multiplayer: a ruleset based on the default but tuned for
            multiplayer games, based on Madeline Book's "rewonder" ruleset
            for 2.1.
          + experimental: a ruleset showcasing new features of the Freeciv
            "engine", without strict regard for game balance and
            playability. It enables some of the new features mentioned
            below, such as variable city radii.
     * More than doubled the number of playable nations (from 185 to 385).
       Many improvements to existing nations, such as using native
       spellings for cities and leaders.
     * The interaction of promotions and diplomat-vs-diplomat contests has
       changed:
          + Attacking diplomats can now gain experience; previously, only
            defending diplomats gained experience. GNA#17265
          + The effect of veterancy on the outcome of these contests has
            been reduced; it can change the odds by at most 20%
            (previously, elite diplomats could become practically
            invincible). GNA#17264
     * The terrain effects of global warming and nuclear winter are now
       more severe: land can be lost to ocean (and vice versa), and
       glaciers can melt. GNA#17105
     * If migration occurs, citizens take half the food in the granary
       with them. GNAPATCH#1232
     * (as of rc1) In rulesets with Fundamentalism, it now has a happiness
       penalty for empire size (as it did in 2.0.x). GNA#18133
     * (as of rc2) The civ2 ruleset now uses a restricted set of 25
       nations, to better resemble the original game. Loading civ2
       savegames from older versions of Freeciv may cause nations to be
       reassigned; it will not be possible to load a civ2 savegame with
       more than 23 (non-barbarian) players. GNA#18419

New features for ruleset/modpack/scenario authors

   These features have been added to the Freeciv "engine", but aren't
   enabled in standard rulesets (except the experimental ruleset, in some
   cases).
     * Variable city radius: the circle of tiles able to be worked by a
       city is no longer fixed but can vary (radii from 1 to 5 possible)
       depending on requirements defined by the ruleset. GNAPATCH#1235
          + Accordingly, the maximum value for the 'citymindist' server
            option has been increased from 5 to 9. GNAPATCH#2262
     * Build slots: in ruleset-defined circumstances, cities with large
       production surpluses can now produce more than one of a given type
       of unit per turn. GNAPATCH#1234
     * Tech upkeep: rulesets can cause some research output to be diverted
       to maintaining expertise in existing technology rather than
       discovering new technology, with the risk of losing advances if the
       upkeep is not met (similar to gold upkeep for city improvements).
       GNAPATCH#1264
     * Rulesets can define units that can be converted into another type
       of unit on the player's command. GNA#13890
     * Rulesets can define "Capturable" units that can be captured by
       certain other "Capturer" units. (There is an associated server
       option 'homecaughtunits'.) GNAPATCH#1851
     * Rulesets can suggest or mandate server settings. GNA#13873,
       GNAPATCH#1200
     * A start position in a scenario can now be restricted to a set of
       nations rather than a single nation. The built-in editor now
       supports editing this set. GNA#13803
     * Various improvements to Lua scripting. See Events Reference Manual
       for some more detail.

Tilesets / Art

     * New default tileset with redrawn terrain graphics: "Amplio 2". The
       original Amplio tileset is available for 2.3 as an add-on (it can
       be found with the freeciv-modpack utility). GNAPATCH#1777
     * Larger versions of flags and shields are now included in the
       Freeciv distribution for use by larger tilesets; they are used in
       Amplio2 (as of beta4). GNAPATCH#2202

Translations

     * (as of rc2) New Scottish Gaelic localization (complete).
     * (as of beta3) New Irish Gaelic localization (not yet complete:
       55%).
     * Updated translations:
          + Complete translations: Polish, French, Spanish, Catalan, and
            British English.
          + Incomplete translations: Danish (95.8%), Finnish (85%),
            Ukrainian (81%), Italian (74%), Japanese (70%), Brazilian
            Portuguese (70%), Russian (69%), Swedish (60%), Lithuanian
            (43%), and Simplified Chinese (40%).

KNOWN ISSUES

     * There are some regressions in the SDL client relative to 2.2.x:
          + The city dialog has not been redesigned to accommodate the
            larger city map required by variable city radius support. As a
            result, the city map display is scaled down and difficult to
            read. GNA#15804
          + Not all setting types can now be modified; bitwise and color
            settings are not yet supported. GNAPATCH#1631 GNAPATCH#1957


MAJOR CHANGES from 2.1.x to 2.2.0
---------------------------------

  (from <http://www.freeciv.org/wiki/NEWS-2.2.0>, 2010-02-21)

     * Built-in editor
     * Expanded ruleset format:

          + Unit classes
          + Movement restrictions

               o Can limit which terrains a unit can enter
               o River-boats
               o Wheeled units
               o Which units another unit can transport

          + Migration
          + Plague
          + Bases
          + Calendar effects

     * Changes to gameplay with default ruleset:

          + New terrains:
               o Deep Ocean (as Ocean but no specials and cannot be
                 transformed)
               o Lake (as Ocean but no Whales special; inland water below
                 a certain size is generated as Lake)
          + Triremes are not restricted to tiles next to land, but to
            (shallow) Ocean tiles; they now cannot even attempt to enter
            unsafe tiles
          + Triremes no longer get the +1 movement bonus from Nuclear
            Power that other sea units get
          + Triremes and Carriers can no longer attack land units
          + Submarine attack strength reduced from 15 to 12 (to make it
            easier to defend against them with escorts)
          + New base type buoy, which can be built by Engineers on water
            tiles with the Radio advance, and gives vision.
          + Ruins (left behind by destroyed cities, no effect on gameplay
            currently)
          + New advance Environmentalism and Solar Plant improvement,
            which can eliminate pollution from production
          + Trade route value now depends on size of cities, not on trade
            generated in them
          + New national borders system
          + Coastal Defense now available earlier (requires Gunpowder
            instead of Metallurgy)
          + No restrictions on specialists in small cities
          + Terrain within working range of a city can no longer remain
            unknown
          + Units in fortresses now regain 25% HP per turn (as in 2.0.x)
            instead of 100%
          + New nations

     * AI difficulty level: Cheating
     * New server options:

          + foggedborders: visibility of borders is subject to fog of war
          + borders gains new modes where player can see all tiles inside
            borders, and borders extend to unknown tiles revealing them
          + endspaceship controls whether spaceship reaching Alpha Cen
            ends the game
          + trademindist controls the minimum distance for trade routes
            between your cities
          + Times now specified in turns instead of years (endyear becomes
            endturn, onsetbarbs expressed in turns)
          + simultaneousphases renamed to phasemode and gains new options

     * Client interface changes:

          + Menus and shortcut keys revamped; notable changes include:
               o Connect with Road/Rail/Irrigation changes from
                 Ctrl+Shift+R/L/I to Shift+R/L/I
               o City Report: F1 to F4
               o Go/Airlift to City: Shift+L to T
               o Wake up Others (Shift+W) becomes Unsentry all on tile
                 (Shift+S)
               o Orders menu split into Select, Unit, Work, and Combat;
                 Reports becomes Civilization

     * Scripting improvements
     * Event cache: messages from the last few turns can be replayed to
       clients on connection and saved in savegames
     * Featured text in Gtk client, including colour coding and clickable
       links to mentioned cities/units/tiles


OLDER CHANGES
-------------

WHAT'S CHANGED SINCE 2.0.7
 - Significantly improved features for modmakers.
 - New default tileset: Amplio.
 - New city tab on main map.
 - City outlines.
 - Added lua as scripting language. New tutorial scenario.
 - Many new nations, flags and nation information and options.
 - New /surrender command to yield in multiplayer games.
 - Score now shown in player dialog.
 - Reputation removed from the game.
 - New borders rules. Borders are static, fortresses expand borders
   and cities expand more borders with city size growth.
 - New diplomacy rules. Neutral state replaced with Armistice. You
   now start in War state, and cannot cross borders with military
   units except in War or Alliance states.
 - GTK+ 1.2 client removed.
 - Votes need over 50% of votes to pass. Voting is now only during game.
 - First player to join becomes game organizer and sets all options.
 - Many AI changes. Improved AI diplomacy.
 - Palace has a production bonus of +75% under Despotism and +50%
   under Monarchy.
 - New animated cursors.
 - Support for GGZ Gaming Zone.
 - Multiple units may be moved at once as a battlegroup.
 - As usual, tons of changes under the hood.

WHAT'S CHANGED SINCE 1.14.2
 - Research cost has doubled, effects of science buildings doubled. SETI
   now improves Research Labs instead of giving free Research Labs to every
   city. Isaac Newton's College now improves all the player's universities.
 - New units: AWACS and Workers.
 - New option: national borders.  Units inside your borders do not cause
   unhappiness under Republic and Democracy.
 - It is no longer possible for one player to be in alliance with a player
   who is at war with another player you are allied with.
 - The Civ2 ruleset now has waste.  Default ruleset does not.
 - Incite costs changed, now cities closer to capital, with units and with
   buildings have much higher incite cost.
 - Killing a defending diplomat now costs you 1 movement point.
 - Units now have multiple, configurable veteran levels.
 - Team mates now pool their research. You may opt out and research
   individually by cancelling the 'Team' treaty.
 - Server has voting on commands and options. You need over 50% of votes.
 - When moving a unit from a transport on an ocean tile to a land tile,
   you lose all movement points.
 - You can specify a list of players that you would like to share victory
   with, using the 'endgame' command.
 - Nations added: Swiss, Afghanistan, Ethiopian, Assyrian, Columbian,
   Elvish, Galician, Hobbits, Indonesian, Kampuchean, Malaysian, Martian,
   Nigerian, Quebecois, Sumerian, Taiwanese, Austrian, Belgian, Phoenician
   and Mexican.
 - New wonder: The Eiffel Tower. Makes AIs love you and improves reputation.
 - The building requirements of several buildings have been changed.
 - The whale special is reduced to 2 food, 1 shield and 2 trade.
 - Settlers / Workers / Engineers can never get veterancy.
 - Trireme's high sea loss now considers veterancy level (green 50%,
   veteran 25%, hardened 5%, elite 0%) before being divided by 2 if you
   have Seafaring or 4 when you reach Navigation (previously only fixed
   at 50% before being divided).
 - Glacier terrain is now unsafe for land units (15% chance per turn of
   being lost). Also doesn't count as coastline for Trireme safety or Fish
   and Whale generation. Roads/railroads can be built but all units (worker
   too) get 15% chance per turn of being lost any way!
 - King Richard's Crusade is now made obsolete by Robotics (previously
   Industrialization).
 - Fixed tech costs based on the number of prerequisites of the tech
   in the tech tree.
 - Nations have preferred nations to fork off when civil war occurs.
 - AI is much improved, and does not use 'double-move' any more.
 - AI now conducts diplomacy with you (and against you).
 - New difficulty level: Novice.  It severely handicaps the AI players.
 - Smarter autoexplorer and autosettler code.
 - Modpack options vastly improved: You can customize buildings,
   add buildings as requirements to units, restrict technologies to certain
   nations, have split technology trees, gold upkeep for units, new units
   and terrain flags and lots of other options.  (This is still done by
   editing configuration files with a text editor.)
 - Fewer popups (eg choose the new government from the menu directly)
 - Alternative map topologies, e.g., real support for isometric and
   hexagonal maps and "donut" map wrapping.
 - Incomplete support for drawing civ3 graphics.  See the civ3gfx tileset.
 - Global observer can observe the entire game.
 - New method of settings map dimensions: Just use 'size'.
 - Modified map generators.
 - Initial units can be selected with a server option.
 - 'Home' key centers on your capital.
 - Drag and drop goto.
 - Player authentication with optional passwords.
 - You can start the server and set server options from the client.
 - You can meet with other players for 20 turns after your units have last
   met, and you can exchange embassies when meeting.
 - You can bind the server to a given IP on multihomed hosts.
 - New client dialog which uses multicast to find servers on your LAN.
 - Compress network traffic and send only a delta (diff) of the data.
 - GTK2 client can now run in fullscreen mode.
 - GTK2 is now the default client (the code base also features fully
   functional GTK1, Xaw and native Win32 clients).
 - Convert charsets as they are sent between client and server.  All data
   files are now in UTF-8.
 - New (and incompatible) metaserver.
 - New ALSA sound plugin.
 - The s(entry) command no longer doubles as a means to put units on
   boats - use the new l(oad) command instead. 
 - Many more (smaller) changes, and massive changes under the hood.

WHAT'S CHANGED SINCE 1.13.0
 - Unique city names, you no longer can name your cities the same,
   and you can enforce unique city names globally (optional).
 - A new map generator (generator 5) which creates pretty fractal
   maps.
 - You can load savegames from the server prompt.
 - You can save client commandline defaults.
 - Specialists are taken from content citizens first, instead of from
   unhappy citizens first. This makes it more difficult to quell unrest
   using taxmen and scientists.
 - You now start with no technologies by default, and angry citizens 
   are enabled by default, although they will rarely make an apperance.
 - The algorithm used for calculating the effects of tax settings has
   been changed. It is now no longer possible to get 100% effect from 
   60% choice of tax goal.
 - A new, historically more correct version of the rulesets included.
 - There is an option to require several turns of rapture/celebration 
   before it takes effect. See "show rapturedelay" in server.
 - The sequence of some end of turn activities have been regrouped.
 - Several AI improvements. It should now build and buy units and 
   buildings slightly more intelligently.
 - Many internal code improvements that will lead to more features
   later.
 - /fix and /unfix commands to stop modifications after game has
   started.
 - The server commands "rulesout", "log", "freestyle" and "crash" 
   have been removed, while "rfcstyle" now toggles between rfcstyle
   and freestyle.
 - civ2 ruleset now more accurately reflects civ2 deity level defaults.
 - A truly massive amount of bugfixes.

WHAT'S CHANGED SINCE 1.12.0

 - Citizen Management Agent (CMA) allows you to automate workers
   and specialists in cities.
 - Sound support has been added.
 - The new "isotrident" tileset has been made the default. The
   "hires" and "engels" tilesets have been taken out of the
   distribution but can be downloaded from the web page.
 - New city dialog in the gtk client.
 - Windows version of the client. It has improved connection
   dialog and supports loading and saving from the client.
 - GTK 2.0 version of the client.
 - The client will try to suggest names for your cities that 
   correspond with what they mean.
 - Improved players dialog shows sortable and colored information,
   including the players' flags.
 - Server no longer takes the --server command line option,
   instead you can use the --info option to set the metaserver
   announcement text to whatever you like. The -a option when given
   to the client skips the connection dialog entirely.
 - A "wall" server command added which gives message to all players.
 - A new flexible timeout set through "timeoutinc" server option.
 - Leftover research bulbs will carry over to next advance.
 - Trade routes are more effective.
 - Units attacking ships in cities double their firepower, while 
   defenders get only 1 firepower.
 - Helicopters defending against air units get 50% penalty, and
   have their firepower reduced to 1 against fighter units.
 - You can build city walls even though you have Great Wall wonder.
 - The Communism government's food cost in default ruleset has
   been changed to 1, while it has been changed to 2 for the Civ2
   ruleset. 
 - Stealth fighter and bomber now really are stealthy, and are
   partially invisible just like subs. Also, stealth bombers have
   increased their attack strength from 14 to 18.
 - Civ2 ruleset now has Fundamentalism.
 - Improved modpack abilities: The caravan ability has been split.
   New ways to calculate technology costs. Better documentation.
   Rulesets can specify starting techs. You can have more than one
   bonus tech. Split settler abilities. Buildings ruleset syntax
   has been significantly extended, but effects do not work yet.
 - Server option "tinyisles" allow 1x1 size islands and 
   "separatepoles" allow continents connected to the poles
 - "citymindist" specify minimum distance between cities, while 
   "notradesize" and "fulltradesize" regulate the trade generated 
   by smaller cities.
 - You can turn on angry citizens with "angrycitizens" option.
 - Fortresses may give you extended vision. See watchtower options.
 - If you lose your palace, you get a new one for free in a 
   randomly chosen city. This behaviour can be turned off with the
   server option "savepalace".
 - Rulesets are now loaded from inside the server through the
   "rulesetdir" command.
 - The limit on the number of nations that can be included with 
   Freeciv has been removed.
 - The format of the isometric tileset spec-files has changed.
 - The map and ai code has been cleaned up significantly.
 - Translations improved. Added better support for plural forms.
 - Several bugs squished and a lot of work done under the hood.
 - For an overview of the remaining bugs please visit doc/BUGS.

WHAT'S CHANGED SINCE 1.11.4

 - Internationalization extended.  Still needs improvement.
   Current localizations: de en_GB es fr hu it ja nl no pl pt pt_BR
   ro ru sv.
 - Isometric view in gtk and amiga clients using the mostly civ2-
   compatible HiRes tileset. This is on by default, but the old non-
   isometric tiles are still available by giving a --tiles argument to
   the client, fx "civclient --tiles trident".
 - While planning a goto (after hitting "g") a line will be displayed
   showing the route from the selected unit to the mouse pointer.
   Hitting "g" will insert a waypoint at the mouse pointer.
 - The server now has readline completion. This works at all levels,
   fx "cu<TAB>" completes to "cut", and if there exist a player named
   "paulz" "cut pau<TAB>" will complete to "cut paulz".
 - Players can agree to give shared vision, which means that you
   automatically see everything the other player sees.
 - Layer view menu items allow you to only display some map info on the
   main map. Fx you can choose to not show roads.
 - The server will ping all connected clients and cut off those too slow
   to respond.
 - Smarter placing of partisans.
 - The server no longer automatically starts when the maximum number of
   players have been reached.
 - If commandlevels are used and the controlling player disconnects a
   connected player can assume the "first" level with the "/firstlevel"
   command.
 - "Restrictions and Limitations" section added to the README.ruleset
 - Caravans, diplomats and spies can move into allied cities.
 - Elephants, Crusaders and Fanatics activated in civ 2 ruleset.
 - The size of the city foodbox is now controlled by the ruleset
   variables "granary_food_ini" and "granary_food_inc".
 - Limit on number of improvement types in rulesets removed.
 - Capitalization is available from the start of the game in the default
   ruleset. (renamed coinage)
 - Cities can have 0 trade. (used to be at least 1)
 - Settlers can only be added to cities less than size 8, as in civ 2.
 - If you paradrop a unit into unknown terrain and the terrain contains
   an enemy unit the paradropping unit is lost. If you drop into terrain
   you thought was land, but which has changed to water, the unit is
   also lost.
 - diplomats/spies can't take action from a ship.
 - Refueling air units at turn update will refuel units with only 1 fuel
   first. Secundary criteria is unit cost.
 - Trireme loss percentage depends upon known technologies.
 - Leonardo's workshop will upgrade a random unit each turn, and not
   just the next one.
 - Allied cities count as friendly when determining whether a unit is
   being agressive. (gives unhappyness under some govs.)
 - Deserts are created primarily 15 to 35 degrees off the equator.
 - Only arctic tiles generated at poles.
 - The server will report when a new government becomes available.
 - Changed wording of message "famine feared" to "famine occurred". New
  "famine feared" message just before food runs out.
 - "wonder soon build" message when another player is about to complete
   a wonder.
 - Players are notified when one of their wonders has become obsolete.
 - In the players dialog it is now reported which nations have an
   embassy with you. Your embassies are also listed.
 - Wonders being built are listed in the "wonders of the world" popup.
 - Server "save" command saves to <auto-save name prefix><year>m.sav[.gz]
   if it is not given any arguments.
 - "quitidle" server commandline option makes server quit if there has
   been no connected players for the specified amount of time.
 - When turning on the autotoggle option existing human nations without
   a connected player will be put on AI.
 - Server doesn't block as long when writing to a slow host, controlled
   by variables "tcptimeout" and "netwait".
 - "savename" server variable controls the prefix of autosaves.
 - "allowconnect" server variable lets you control which types of
   players (new players; human players; AI players; dead players;
   barbarian players) can connect.
 - More nations added.
 - New maps in data/scenario: british-isles-80x76-v2.51.sav,
   iberian-peninsula-136x100-v0.9.sav,
   hagworld-120x60-v1.2.sav (earth map).
 - Amiga internationalization/localization.
 - Amiga client: history added to chatline.
 - Lots of bug fixes and code cleanups.

WHAT'S CHANGED SINCE 1.11.0:

 - Readline support added to the server.
 - May now disperse initial units over specified area.  See "dispersion"
   server option.
 - May now arrange for first client to connect to have a higher cmdlevel
   than the following clients.  See "cmdlevel" server option.
 - Save files now transparently (un)compressed when (loaded) saved.
 - Now requires a minimum number of ocean tiles to be adjacent to a land
   tile wished to be transformed into ocean.  Default is 1.
 - Added Nuclear Fallout.  Industrialization and population still
   generate Pollution.  Dropping a Nuke generates Nuclear Fallout, which
   is distinct from Pollution.  There is a new command to clean Fallout
   vs. cleaning Pollution.  Fallout contributes to Nuclear Winter --
   which also changes terrain, but tends to Desert, Tundra and Glacier.
   Added a new "cooling" icon to the info area to indicate the progress
   towards Nuclear Winter, and also an icon for Fallout on the main map.
   AIs are now more aggressive at cleaning up Pollution, but not Fallout.
 - Ported to OpenVMS.
 - Moved most of the dependencies on the "civstyle" server option to
   separate values in game.ruleset files.
 - Fixed bugs in "turns to build" displays.
 - Fixed bug whereby Diplomat/Spy investigations of cities did not
   reveal the correct supported and present unit lists.
 - Fixed multiple bugs in go-to code.
 - Fixed bug where starting a revolution, saving the game and restarting
   the server would allow switching governments without anarchy.
 - Fix bug that you could paradrop into cities you were at war with even
   if they contained enemy units.

WHAT'S CHANGED SINCE 1.10.0:

 - Internationalization extended.  Still needs improvement.
   Current localizations: de en_GB es fr hu ja nl no pl pt pt_BR ru.
 - Added full Fog of War.  Controlled by "fogofwar" server option.
 - Added explicit Diplomatic States between civilizations: war, neutral,
   no-contact, cease-fire peace and alliance.
 - Allow terrain changes to/from land/ocean.  Default ruleset allows
   Engineers to Transform Swamp to Ocean and Ocean to Swamp.  Also
   allows Forest to be Mined into Swamp.
 - Increased maximum number of players to 30.
 - Fortifying now takes a turn to complete (like Civ1/2).
 - Added correct Civ2 style of Apollo wonder (shows entire map, rather
   than just cities).  Selected by "civstyle" server option.
 - Aggressive sea units no longer cause unhappiness when in a city.
 - Added Civ2 rule that firepower is reduced to 1 for both the defender
   and the attacker when a ship bombards a land unit.
 - When changing current research, if user changes back to what was being
   researched, the penalty is not applied (you keep all your bulbs).
 - Added pop-up of more details when clicking on info box in GTK+ client.
 - Improved the global warming danger indicator.
 - Added warning of incipient city growth.
 - The server "remove <player>" command is no longer available after the
   game has started.
 - Added "fixedlength" server option to make all turns exactly "timeout"
   duration.
 - The "timeout" time may be much longer (up to a day).
 - Added goto for air units.  If destination is beyond range, they will
   stop in cities/airfields/etc. to get there.
 - May now select a unit by clicking on the unit pile display on the left.
 - Diplomats/Spies moving by goto now do pop-up the Diplomat/Spy command
   dialog when they reach a city.
 - Improved goto algorithm and implementation.
 - Help dialog displays which buildings an advance will obsolete.
 - Optionally show city food/shields/trade productions on main map.
 - Added server option "autotoggle", which toggles AI status on and off
   as players connect and disconnect.
 - Allow Hoover Dam to be built anywhere, to conform to Civ2.
 - Show turns per advance in Science Advisor dialog.
 - Improved map and unit movement drawing code.
 - Added "End Turn when done moving" local option.
 - City production penalties now applied more correctly.
 - Added Sentry and Fortify to Present Units' City Dialog pop-up.
 - More nations added.
 - Added a resource file for the GTK+ client.
 - Improved network code for more reliable connections.
 - Split nations.ruleset into individual <nation>.ruleset files.
 - Extended registry file format to allow including files and overriding
   entries.
 - Added --with-xaw and --enable-client=xaw3d options to ./configure
   script.
 - Lots of bug fixes and code cleanups.

WHAT'S CHANGED SINCE 1.9.0:

 - Internationalization extended.  Still needs improvement.
   New ./doc directory for localized versions of README and INSTALL.
   Current localizations: de en_GB es fr hu no pl pt pt_BR ru.
 - Added Civ1/2-like Barbarians.  Controlled by two server options.
 - Many more nations added.
 - Worklists -- Players can now specify a list of things to be built in
   a city.
 - The AI now utilizes diplomats/spies aggressively.
 - Added a variant (1) of Michelangelo's Chapel.
 - Initial rates after Revolution will try to maximize Science.
 - Rapture-triggered city growth will no longer empty the foodbox.
 - Map generator improvements:
   - Gen 1 hills more uniform north/south.
   - Gen 2+ will tend to make fewer length-one rivers.
 - Added unit-death explosion animation.
 - No longer will cities with exactly 0 (zero) production surplus be given
   a "free" shield every turn.
 - Command-line arguments made more consistent between server and client.
 - Caravans now provide a research benefit when initially establishing a
   trade route, equal to the monetary benefit.
 - Diplomat/Spy changes:
   - Changed all actions to more closely conform to Civ2 rules.
   - Changed "diplchance" to be %-chance of success.  Used in many ways.
   - Diplomat/Spy may attempt action with any movement left.
   - Added "At Spy's Discretion" selection to steal and sabotage dialogs.
   - Allow Spies to steal tech from a city more than once (gets harder).
   - May only poison towns of size greater than 1 (one).
   - May only sabotage units that are alone on a square.
   - When a city is subverted, only nearby units change sides.
   - Veteran status improves defense against other Diplomats/Spies.
 - Added production display of number of turns remaining to build.
 - Small, shield-like flags tilesets (trident_shields, engels_shields).
 - Airbase changes (for Civ2 compliance):
   - Ground units can attack Air units when they are parked on an Airbase.
   - Units are defeated only singly when on an Airbase (like a Fortress).
 - Revised and improved the server 'help' command.
 - New intro graphics.
 - Ships may now have their movement reduced after a combat in which they
   are damaged.
 - Added display of production values to main map "city tiles" display.
 - Increased the Add-To City size limit to 9 to conform to Civ2.
 - Settler's "Connect" feature -- Automatically connect two points with
   Road, Railroad, Irrigate or Fortress.
 - Several AI improvements.
 - New ruleset support for CITIES, most notably cities are now drawn in
   different sizes and styles.
 - Allow specifying unambiguous player name prefix, instead of full 
   player name, for server commands taking a player name argument.
 - Added multi-client configuration support.
 - Added 'read' and 'write' server commands.
 - Added "best nation" column to Demographics report.
 - Changed Fighters and Stealth Fighters to not cause unhappiness (Civ2).
 - Cities on mountains will produce an extra food (Civ2).
 - Fixed bug where Lighthouse was not producing veteran sea units.
 - Ported to Amiga.  (This is not included with a "distribution"; get it
   directly from the CVS <http://www.freeciv.org/contribute.html#SetupCVS>,
   or from a CVS Snapshot <http://www.freeciv.org/latest.html>.)
 - Lots of bug fixes, code cleanups, and help-text improvements.

WHAT'S CHANGED SINCE 1.8.1:

 - Internationalization added.  Some aspects still need improvement,
   and in particular currently only works well if client and server
   both use the same language.  Initial (partial) translations
   included are: de es fr hu pl pt pt_BR.
 - Improvements to "trident" tileset, and this set is now the default.
 - New ruleset support for NATIONS, and many new nations added --
   there are now 32 nations in the default nations file.  Also allow
   multiple leaders choices for each nation, allow longer player
   names, and allow specifying/choosing sex of leader.
 - New ruleset support for TERRAIN, and changes to allow Civ2 style
   terrain with more specials, multi-terrain rivers, and new farmland
   infrastructure.  Moved some server options into terrain ruleset,
   and added new rule option regarding movement along rivers.
 - New ruleset support for GOVERNMENTS, and more general unit upkeep.
 - The contents and layout of the graphics files is now described in
   user-editable 'spec' files, instead of being hardwired into the
   code; see README.graphics for details.
 - Changes to city graphics: can now see cities grow.  Also, code
   support for different city styles for different nations, and for
   technology dependent styles, but lacking good graphics except for
   the default style.  Cities show a small flag when occupied by one
   or more units.
 - From Civ2, added Paratroopers unit and Airbase infrastructure.
 - Initial window size of Gtk+ client is smaller, to fit better on
   smaller screens, and can now resize detached chat/output window.
 - City report enhancements: New "Change All" dialog to convert all
   production of a given item to some other item (both clients); can
   select multiple cities and issue commands (Gtk+ client only); can
   sort by different columns (Gtk+ client only).  Can also select
   multiple items in the Trade Report (Gtk+ client only).
 - In Civ2 style, can select which infrastructure item to pillage, and
   multiple units can pillage together.  Can now pillage fortresses,
   as well as new farmland and airbase infrastructure items.
 - More fields added to Demographics Report, and now configurable from
   a server option.
 - Added more information to "Active Units Report", and renamed to
   "Military Report".
 - New cursors added for Goto, Nuke and Paradrop modes; <Escape> key
   cancels Go-To/Paradrop/nuke mode; pollution on city squares is now
   always clearly visible; improvements to refresh method for pixmaps
   in Gtk+ client; various other improvements to both clients.
 - Autosettlers no longer convert Plains/Grasslands to Forests, but
   will now Transform terrain.
 - AI can build spaceships, although does not do so very aggressively
   or intelligently yet.
 - Server and client may specify a different metaserver to use.  There
   is now a metaserver running on www.freeciv.org, and that is now the
   default metaserver (http://www.freeciv.org/metaserver).
 - New server option for "turn blocking" mode, in which players will
   never miss a turn even if sometimes disconnected.
 - More flexible rulesets for units and techs (advances) allowing
   variable number of items in each (up to 200) and no longer any
   techs with hardwired effects depending on position in ruleset file.
 - Appropriate helptext now appears in ruleset files, allowing
   modpacks to give modified help to correspond to modified items.
 - Format of ruleset files is changed, no longer compatible with
   those for 1.8.0 and 1.8.1.
 - Removed science bonus of +1 per city per turn.
 - In Civ2 mode, overflight of a hut causes it to disappear, and can't
   build cities next to each other.
 - Rapture_size now 3, to conform to Civ2.
 - Settlers and Engineers now cost shield upkeep as well as food
   upkeep (depending on government type) as in both Civ1 and Civ2.
 - Helicopters do not lose hitpoints when over an airbase.
 - The amount of food required for a city grow is now ((citysize+1) *
   foodbox), instead of (citysize * foodbox); new behavior matches
   both Civ1 and Civ2.
 - Some re-organization of data directory, in adding data/scenario,
   and graphics now in data/trident, data/engels and data/misc.
 - Preliminary support for compiling the server on Mac (but networking
   code not yet ported).
 - Progressively moving code out of client gui-dependent directories.
 - Lots of bug fixes, code cleanups, and help-text improvements.

WHAT'S CHANGED SINCE 1.8.0:

 - The biggest change is a new client which uses the popular Gtk+
   toolkit.  The old Xaw client is still included as well.
 - A new alternate (30x30) tileset: the "trident" tileset.
   Start the client with "--tiles trident" to try it out.
   (This replaces the "classic/brunus" tileset, which is still
   available separately from the Freeciv ftp site.)
 - In the Gtk+ client, parts of the main window can be detached.
   Detaching them all allows a full-screen map window!
 - The data directory can now be specified as a "path" ($FREECIV_PATH),
   instead of a single directory.  By default, ~/.freeciv is now in
   the path, so if you download new tiles, modpacks, etc, you can now
   simply put them in ~/.freeciv
 - Server console improvements: can abbreviate server command names,
   and server option names.  Better prompt handling - eg, server no
   longer prints an unnecessary prompt each turn.
 - Server commands can now be issued from the client chatline.
   There is a new server command "cmdlevel", to control access to
   this feature on a per-player basis.
 - Some of the "small" graphics have been improved.
 - Added a nice cursor for selecting the destination for "goto".
 - New column "corruption" in the city report.
 - Implemented Marco Polo's Embassy wonder.
 - New command to explode Nuclear units at an empty square.
 - Improved behavior of Caravans and "goto": the Caravan dialog will
   now popup when the Caravan arrives, whether moving by goto or by
   the keyboard.
 - Allow connecting to metaserver (in client) via $http_proxy.
 - Minor "Zone of Control" (ZOC) rules changes to better match Civ2.
 - Improved debug logging.
 - Server will refuse to run as root, as a security measure.
 - As always: lots of bug fixes, code cleanups, and help-text
   improvements.

WHAT'S CHANGED SINCE 1.7.2:

 - Space race!  Be the first player to build a space ship and colonize
   Alpha Centauri.
 - Civil war!  Capturing the enemy capital may split his empire.  Half
   of his towns will join a new AI leader!
 - Two tile sets in this release! The "big" ones are from Ralph Engels.
   I hope you will enjoy them.  The second set is an enhancement of the
   classic ones.  The server option -tiles allows to choose a subdirectory
   of the data directory to use different tiles.  (The data directory can
   be set with the DATADIR environment variable.)  Also, diagonal roads
   and railroads are now drawn.  Changed some of the national flags
   (especially changed Soviet flag to the Russian flag for Russians).
 - Rulesets can be used to customise units, advances, wonders, and
   improvements without recompiling -- see README.rulesets.
 - Units in a town can be put in auto-attack mode.  In this mode, they
   will attack any enemy units which come nearby.
 - New city options for each city, controlling whether new citizens are
   workers or specialists, whether to allow disbanding a size 1 city by
   building a settler, and options for units on auto-attack mode in the
   city.
 - Mapgen 4 (selected with the server command "set generator 4") is a new
   map generator which generates a map with 2 players on each island.
 - Cities can be a traded in diplomatic treaties.  This effectively
   allows you to exchange, sell or buy cities.
 - The AI now builds diplomats to defend against enemy diplomats.
 - Settlers and engineers can do teamwork.  With enough manpower, all
   terrain improvements can be done fast!
 - With engineers, the terrain type can be changed using the new Transform
   command ('O').  For example, hills can be turned into plains.
 - Units only regenerate hit points if they have not moved at all for a
   full turn.
 - Gamelog option.  The whole history of a game can be stored in the
   gamelog file.
 - One can select a unit with 0 moves left from the main map.
 - City workers can be adjusted from the main map, with shift+button1.
 - Changed the order of libraries to fix problems on IRIX and Cygwin.
 - Changed the client-server protocol to use network byte order.
 - Other bug fixes and code and help text cleanups.

WHAT'S CHANGED SINCE 1.7.1:

 - Improvements to the configure script, so it should now work
   properly on all systems.
 - Ability to configure to use Xaw3d instead of the normal Xaw.
 - New "easy" AI mode, which is now the default.
 - Improved "City Report" dialog, with configurable columns.
 - Improved "Message Options" dialog, with customizable filtering and
   selection for the different message types.
 - Improved "Messages" dialog, with a scrollbar, and a "Popup City"
   button.
 - Improved multi-column "Unit Select" dialog when there are lots of
   units.
 - In city dialog, middle-click unit icons to "activate and close".
 - New client command "t" to show tiles used by city under mouse.
 - New metaserver dialog to make connecting to metaserver games easier.
 - Ability to save and re-load client settings.
 - Clearer Yes/No toggle buttons in various places in the client.
 - Reduced color usage (but looks almost identical), so the client should
   now work fine on systems with 8 bit color displays.
 - Ability to use "scenarios", that is, pre-designed maps.  Scenarios
   for Earth and Europe games are included in the data directory.
   (Use them with the server command-line option -f, like savegames.)
 - More city names, so you're less likely to see "City 41" etc.
 - Saving large games is now much faster, and the savefile is smaller.
 - Improvements to the documentation and online help system, including
   a new help section on the "Zones of Control" game concept.
 - Detect repeated log messages and print repeat counts.
 - New server options randseed and aqueductloss.
 - Many other enhancements and bug fixes.

WHAT'S CHANGED SINCE 1.7.0:

 - Removed two C++-style comments, the most reported problem with 1.7.0!
 - Tweaks to the configure script for Solaris, although it's still not
   perfect.
 - Spy and diplomat improvements.
 - Added the "W" command, which Wakes up sentried units.
 - Added the "scorelog" command, which can be read by a script to generate
   power graphs after the game.
 - Loading games is now MUCH faster.
 - AI improvements from John Stonebraker.
 - Visual improvements to dialogs and the map screen.
 - Settlers may not fortify.
 - Numerous bug fixes.

WHAT'S CHANGED SINCE 1.6.3:

 - Massive AI changes. It plays smarter, and the AI uses seagoing vessels.
 - The contents of the help system have been improved substantially.
 - Many bugs fixed.
 - We now recommend you use "configure" instead of Imake.
 - Settlers have a new "e"xplore mode.
 - The makefiles now contain auto-generated dependency information.
 - Units within the radius of the city to which they belong no longer
   cause unhappiness.  This will allow much more realistic defense
   scenarios.
 - The tax/lux/sci rates are now limited by your government type.
   Also, they can modified by clicking on the rate status icons.
 - The behaviour of spies and diplomats has been greatly improved.
 - Freeciv now needs to transmit a lot less data (<25%!) when playing
   over the Internet.  This will greatly speed up games.
 - Preliminary support for compiling Freeciv under Windows and OS/2,
   when used in conjunction with the GNU tools.
 - From now on, it will be possible for different Freeciv versions to
   talk to each other if they're able.
 - Tracy Reed (who provides www.freeciv.org) reports that our site is
   getting over 6,000 hits per month.  He was quoted as saying "Cool!
   Now my computer is doing something!"
 - Lots, and Lots, and Lots of donated patches. Thanks guys, keep 'em
   coming!
