NEWS-2.6.0

= Welcome to Freeciv 2.6.0 =
Thanks again to all our developers, who continue to work so hard. Special thanks go to:
* Emmet Hikory and pepeto for the pathfinding rework
* Sveinung Kvilhaugsvik for generalized actions
* Marko Lindqvist for generalized extras
* mir3x for the Qt client
* GriffonSpade for the Hexemplio tileset and other art updates
This release includes lots of changes relative to 2.5.x; the significant ones are outlined below. Bug fixes also included in the 2.5 line are not listed. Those who are interested in seeing the detailed changes should check the ChangeLog file, linked above.
= What's changed since 2.5 =
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). 
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). 
* 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.) 
* Buoys no longer claim territory, and so can no longer be used to block travel during peace. 
* The size of barbarian uprisings, and the effect of the 'barbarians' setting, have changed. (It's not clear what the old code actually did.) 
* 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.) 
* (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). 
* "Industrial Accident" disaster, where a Mfg. Plant can cause population loss and pollution. 
* 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). 
* "SDI Defense" now works against allies' nukes. 
* 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. 
* Ruins are removed whenever the underlying terrain is changed. 
Rule changes to specific rulesets:
* civ2civ3 has had many changes.
** Units and combat
*** 'Tired attack' is enabled: units that attack with less than one movement point have reduced attack strength. 
*** 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.) 
*** Naval units are now generally cheaper, to make the ratio of strength to cost more similar to land units. 
*** 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. 
*** Cruise Missiles have increased range, and can target aircraft.
*** All aircraft can use Airports to travel between cities.
*** 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.) 
*** Only "Big Land" class units (tanks, artillery etc) kill citizens when attacking a city; "Land" class units (infantry etc) no longer do. 
*** Triremes are subject to ZoC when traveling on rivers, and can no longer move diagonally between river tiles.
*** Explorers can establish embassies and investigate cities, like Diplomats. They are slightly more expensive, but do not become obsolete.
*** The actions Establish Embassy and Investigate City can be done directly from a boat.
*** Diplomat and Spy can fortify (this provides no defensive bonus, but means they don't wake up as they would when sentried). 
*** Reworked merchant units (Caravan and Freight) and trade. 
**** 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.
*** The default start units include a Worker instead of Migrants. 
** Terrain and terrain alterations
*** 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 ; 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).
*** City centers once again always get automatic roads, even on rivers without knowledge of Bridge Building. 
*** 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. 
*** Mountains now get an extra production point from mining (changed from +1 to +2).
*** 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. 
*** 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.
*** Added Maglevs (with Superconductors), which supplement Railroads and give infinite movement to certain units.
*** Forest, Jungle, and Swamp tiles now give the advertised defense bonus of 25% (in 2.5 it was rounded down to 20%).
*** Forest and Jungle tiles can now suffer pollution and fallout, like most other tiles. 
*** 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. 
*** Adjusted effects of climate change. Ocean can no longer become Deep Ocean. 
** Buildings and wonders
*** Great Wonders are now only obsoleted when the owner learns a certain technology, not when any player does. 
*** A new building, the Ecclesiastical Palace (available with Theology), acts as a second center of government. 
*** Spaceship part cost approximately doubled. 
*** It's no longer possible to build a Harbor next to a lake (since it gives no benefit to lake tiles). 
*** Conversely, Lighthouse and Magellan's Expedition can be built next to deep ocean. 
*** The suppression of Super Highways trade benefits by a farmland bonus no longer applies to city center tiles. 
** Technology
*** '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). 
*** Construction now requires Iron Working, rather than Currency (so that Iron Working is a prerequisite for Frigates and Ironclads). 
*** Population pollution can now occur even without knowledge of Industrialization. (This was a corner case that would likely never have been encountered.) 
** Government
*** The Tribal government gives one content citizen per city instead of martial law.
*** Tribal governments get an extra unhappy citizen at a slightly smaller empire size, and Monarchies at a slightly larger.
*** Each city in a Federation gets 2 extra luxury points.
*** 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.)
*** Similarly, the luxury loss from Anarchy is now additive rather than multiplicative.
** Other
*** 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. 
*** 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.) 
*** Adjustments to AI bonuses: 
**** 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.
*** Tweaked the startup defaults. (These are almost all server settings that can be customized to taste.) 
**** 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. 
** Darwin's Voyage now only gives one free tech, not two. 
** Buoys have been restored, now that they no longer claim territory. 
** 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. 
* 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. 
** Spies can bribe and sabotage units which are not alone on their tiles. 
** 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. 
** The fourth city radius on square topologies is slightly larger. 
* 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). 
** In the civ2 ruleset, Diplomats and Spies can now perform their actions directly from a ship on the ocean. 
** Player colors are by default tied to specific nations. 
** The civ1 ruleset no longer has Farmland (previously it existed despite being impossible to build, due to engine limitations). 
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. 
* The 'diplcost' setting has been split into 'diplbulbcost' and 'diplgoldcost'. 
* 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. 
* The 'happyborders' setting has a new value which allows your units to be inside allies' borders without causing unhappiness. 
* 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'). 
* 'citymindist' now goes up to 11. 
* 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'). Also, this setting can now be empty if 'startcity' is set. 
* 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. 
** The previously hardcoded suppression of relief at the poles is now controlled by a new setting 'flatpoles'. 
** Narrower borders around edged maps (restoring 2.2.x behavior). 
** Map generation now tries a bit harder before giving up. 
Game limits:
* The maximum number of regular players has increased from 126 to 150 (160 including barbarians). 
* The maximum number of cities and units in a game (added together) has increased from 65535 to 250000. 
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".) 
* 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. 
=== 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 . 
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.
Existing rulesets need changes to work with 2.6; see 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. 
** 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:
*** 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. 
*** Extra removal (cleaning and pillaging) can now have additional requirements (rmreqs).
*** 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).
*** Extra build/removal time can now also depend on both extra and terrain to some extent (build_time_factor, removal_time_factor).
*** Extras can optionally disappear when the underlying terrain changes even if they would be valid on the new terrain -- 'TerrChangeRemoves' extra flag. 
*** 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. 
*** 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. 
*** Integrating roads, allowing move bonus / legality between two tiles with different types of roads. Graphics are drawn appropriately. 
*** 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'. 
*** Extras can now be native to units without also being refuel points for them ('Refuel' extra flag). 
*** 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". 
*** 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 .Some examples of newly possible things (this is not an exhaustive list):
*** Helping to build a wonder in a foreign city.
*** Sabotaging a unit with 1 hitpoint can kill it.
*** Poisoning a size 1 city can destroy it.
*** Acting against units not alone on a tile (the player is prompted to choose a target unit).
*** Acting against units inside cities (but you must be able to see inside the city, implying at least Alliance).
*** Hostile actions against players you're not at war with, or yourself.
*** Establishing embassies with No_Diplomacy nations.
*** 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"). 
** "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.
*** Rulesets control the numeric criteria for cultural victory (which is optionally enabled with the 'victories' setting).
*** Requirements can test the total culture of cities or players.
*** 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 ), 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. 
* Terrain
** Terrain defense bonuses that aren't a multiple of 10% now work as expected (previously they were rounded down to the nearest 10%). 
** Map generation:
*** 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.
*** 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. 
* 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:
*** 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. 
*** Path-finding through unknown terrain makes different decisions. 
*** Auto-explore works better with units other than pure land/sea units. 
*** Unreachable target units are handled better by path-finding. 
*** As part of this, the old 'move_type' ruleset parameter has been completely retired; the engine infers what it needs from other unit properties. 
** Units no longer have to impose zones of control (ZoC); this can be disabled with the 'HasNoZoc' unit type flag. 
** The hardcoded rule that units may only impose a zone of control (ZoC) on land has been replaced by the 'NoZoc' terrain flag. 
** 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. 
** The hardcoded rule that units may fortify on land but not water has been replaced by the 'NoFortify' terrain flag. 
** 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. 
** A new ruleset option 'pythagorean_diagonal' allows diagonal moves in square topologies to cost more than orthogonal moves. 
** The maximum paradrop range has been increased from 255 to effectively unlimited. 
** Rulesets now have better control over which unit types can be granted via 'startunits', with the '*StartUnit' role flags. 
** The maximum number of ruleset-defined unit type flags has increased from 16 to 32. 
* 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'. 
** 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). 
** 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'). 
** 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. 
** 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). 
* Trade
** Trade route legality / bonus can now differ depending on whether foreign trade routes are with an enemy, ally, or team member. 
** Whether trade routes give a one-time bonus to gold and/or science is now configurable. 
** The new 'Traderoute_Pct' effect allows ongoing trade route revenue to be adjusted. 
* 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). 
** 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. 
* 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.
*** One Animal Kingdom AI "barbarian" player is created at game start to manage the animals.
*** 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.
*** 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.
*** The map is randomly populated with animal units according to map size and terrain availability at game start (controlled by the new 'animals' setting).
*** 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. 
* Effects and requirements
** New requirements:
*** 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). , 
**** The unit's veteran level (MinVeteran). 
**** The unit's remaining movement points (MinMoveFrags). 
**** The unit's remaining hit points (MinHitPoints). 
*** '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. 
*** The 'MaxUnitsOnTile' requirement allows testing the total number of units currently on the tile. 
*** New requirement 'Age' allows testing how many turns a unit, city, or player has existed. 
*** '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. 
*** 'Topology' tests properties of the game's map topology ('WrapX', 'WrapY', 'Iso', or 'Hex'). 
*** A new value 'Claimed' for the 'CityTile' requirement allows testing whether a tile is inside any player's borders. 
*** 'BaseFlag', 'RoadFlag', and 'ExtraFlag', allowing testing whether extra has certain properties rather than just its type. 
*** The new requirement 'Extra' replaces 'Special', 'Base', and 'Road'.
** New requirement ranges:
*** 'Alliance' and 'Team' allow testing whether any player in these sets has a particular property. 
*** 'Traderoute' allows testing whether any city with which this one has a trade route has a particular property. 
** 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:
*** The new 'Victory' effect allows the ruleset to add any win conditions that can be expressed with the requirements system. 
*** 'Unit_Bribe_Cost_Pct' allows bribe cost to be adjusted. Bribe cost reduction for settler-like units is now under ruleset control. 
*** The 'Nuke_Proof' effect can now depend on diplomatic relationship. 
*** '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. 
* Calendar
** Rulesets can now define sub-year divisions in their calendar. The new 'Turn_Fragment' effect controls how many fragments pass each turn. 
* 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. 
** Unit classes can have custom help text. 
** Rulesets can contain a version number field, which is reported in help, on the metaserver, saved in savegames, etc. 
* Lua scriptingWhile old scripts should mostly continue to work, see how to update a lua script from 2.5 to 2.6 to avoid deprecated constructs. See the 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. 
** (Terrain):class_name() ("Land" or "Oceanic") 
** (Direction):next_cw(), next_ccw(), opposite() 
** (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. 
** 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) ; and (Player):research_name_translation()/research_rule_name(), to name that group .
** New 'city_transferred' signal, which is triggered whenever a city changes hands for any reason. 'city_lost' is deprecated in favor of this one. 
** New 'city_size_change' signal, superseding 'city_growth' and allowing script reaction to famine, etc. 
** Methods to test some city properties: (City):is_happy(), is_celebrating(), is_unhappy(), is_gov_center(), and is_capital(). 
** Methods to navigate unit transport stacks: (Unit):transporter(), (Unit):cargo_iterate(). 
** (as of RC2) find.role_unit_type() can now find a unit with a given flag, as well as a given role. 
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 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). 
* Activity icons for removal of pollution/fallout type extras can be specific to the extra type. 
* Can specify an alternative layout for unit upkeep sprites ('unit_upkeep_small_offset_y'), for better display in the SDL clients. 
* Various elements now have configurable offsets, allowing more condensed graphics files.
* Can specify seperate pixel_border_x/y. 
* Tilesets can have a summary and description, which are displayed in the client in "About Current Tileset". 
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.) 
* Saltwater ocean flooding freshwater lakes can be disabled for specific scenarios. 
* There's an optional 'authors' property. 
* Scenarios can be marked as 'handmade', causing a warning about data loss when modifying them in the built-in editor. 
* It's now possible to set a player's government type in the editor. 
* Scenarios saved from the editor tended to be saved with fixed game/map random seeds which affected play. This no longer happens. 
* 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. 
=== Changes affecting server operators ===
* It's now possible to /create an AI player with specified AI type but random name/nation. 
* 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. 
** 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'. 
** 'scoreloglevel' controls whether AI players are included in the scorelog. 
* 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. 
** 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. 
** The history report is now saved, and sent to players who join mid-turn. 
** 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. 
* Various dotfiles that lived directly under the user's home directory now live under the ~/.freeciv/ directory -- notably client settings (.freeciv-client-rc-*) and server command-line history (.freeciv-server_history) .
* 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. 
* Loading saved games from Freeciv before 2.0.x is no longer supported. 
=== 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). 
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.) 
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. 
** The AI was not building defender units when it wanted a defense building but was frustrated. 
** The AI was overoptimistic about defense strength when choosing what defender to build. 
** The AI has a more nuanced understanding of which buildings defend against particular unit types. 
** The AI no longer considers harmless units (such as civilians and those that can't attack) a danger. 
** If an AI diplomatic unit can't bribe a nearby unit in self-defense, it will consider sabotaging it instead. 
* Attack
** The AI is more willing to build attacker units. 
** The AI now prioritizes particular cities for conquering. 
** 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. 
* 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. 
** If a city's food store is full and it is blocked from growing, the AI will prioritize production rather than food. 
** The AI will now build military units purely for their martial law effects. 
** The AI likes to build great (unique) wonders more than it used to. Once it's started, it's less likely to stop. 
** 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. 
** The AI tended not to switch from building units to buildings, even though it suffers no penalty for doing so. 
** General improvements in AI's evaluation of building usefulness. 
** AI players will now consider establishing trade routes with peaceful nations, not just allies (although allies are still preferred). 
** AI cities will not build endless caravans if already built ones are piling up. 
** The AI's selection of ferries for settler units is improved. 
* Research
** The AI considers researching technologies for effects that they grant directly. 
* Government
** AI now evaluates governments' effects directly, relying less on ruleset hints to choose a government. 
* 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). 
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. 
The stub AI can now be linked in statically. This makes it easier to set up a game where effective AI players are prohibited. 
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 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). 
* A new player created by civil war gets the same AI type as the victim. 
* 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. 
* 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. 
== 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. 
* 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. For patrol orders, the return path is shown. 
* 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. 
** 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'. 
* A new option to suppress autocentering and animation for automated units (such as autosettlers). 
* 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. 
* When loading a savegame, sounds are no longer played for events whose messages are displayed from the cache but took place in previous turns. 
* The full-screen preference is now saved separately for each different client type. 
* The city report now has a "continent number" column, mainly to allow sorting such that cities on the same continent are grouped together. 
* 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. 
* A new option to remember the last server connected to. 
* 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.) 
* Client settings (such as tileset and menu music) are now available from a button on the start screen of the Gtk and Qt clients. 
* (Gtk3) The allowed ranges for the city governor can now be adjusted. 
* (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.) 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. 
** Quick airlift: with a single click, airlift as many units of a specific type as possible from other cities to the target city. 
** Rally points: can specify that newly built units go to a particular tile. 
** Trade planning: suggest trade routes between a set of cities (including those not yet built), and automatically send caravans to implement the plan. 
** "Wake up": the client can play a sound on receiving a specific string. 
== 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. 
* Modpack specifications may now contain relative URLs, allowing them to be copied from one server to another without modification. 
* The modpack installer can easily be built pointing to a different modpack list server (--with-modlist). 
== 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.) 
== 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). 
* 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. 
* 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). 
* 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. 
See for more information.
= What's changed since 2.6.0-RC2 =
For those who've been trying the betas, these are the changes since the last release candidate, 2.6.0-RC2:
* The server could crash after loading a savegame where any player was using worker tasks. 
* With recent versions of Qt, the Cancel button wouldn't appear on the popup to choose a city's production. 
* The Qt client's unit help tooltip could show extra garbage. 
* The Amplio2/Cimpletoon tilesets have a more visible Pollution sprite. 
* Updated translations: French (complete), Finnish (98.4% core, 91% nations), Spanish (93% core, 97.4% nations), Japanese (89% core, 95.8% nations).
= 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. , 
* The new tileset selection arrangements can still be a little confused/confusing. 
* The Gtk3 clients' theming has bugs with recent versions of Gtk3. 
* The Gtk3 clients' zoom function still has some glitches. 
* The Gtk3 clients currently don't have animation for moving the map view. 
* The SDL2 client is still more flakey than SDL in various ways.
* The SDL clients have no UI for manipulating policies. 
* We suspect there are still some bugs lurking in the music soundtrack system.
Category:NEWS