This is a FOSS (Free / Open Source Software) implementation of the VideoGame/{{Civilization}} family of turn-based strategy games. Several rule sets are provided allowing for different types of game behavior. In addition, because the source code to the game itself is available, a sufficiently motivated and knowledgeable person can implement changes to the game's behavior beyond anything possible merely by changing the rule set the game uses, including behavior not found in the commercial precursors to this game.

Most things involving it (including downloads) can be found at [[http://freeciv.wikia.com/wiki/Main_Page its wiki]].
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!!Tropes featured include:
* ArtificialStupidity: Computer players are extremely stubborn with "their" territory build a city on any square they consider to be "theirs," and they'll raze the city without any diplomacy scene or change in relationship. In fact, if you then attack one of their cities, ''they'll blame you for starting the war''. They never offer you any trades. They are also incapable of building trade routes (in order to boost luxury and grow their city with celebrations), at least at easy difficulty.
* BoringButPractical: The ''Adam Smith's Trading Co.'' wonder makes all basic buildings that normally cost one gold per turn upkeep-free. Might not sound like much, but free granaries, harbors, temples, banks, libraries can get you a long way and allow you to allocate more taxes for research because of how much less you have to spend on first-level buildings. Also, it never becomes obsolete.
* BreadAndCircuses: You can alter your nation's priorities between taxation, science and luxury. The higher you set your luxury priority, your citizens will be happier and less likely to cause disorder. Ironically, this is most important under a Republic or Democracy.
* CorruptPolitician: [[CloakAndDagger Spies]] and [[AssInAmbassador diplomats]] can be paid to "[[StagedPopulistUprising incite a revolt]]" in non-allied cities as a "[[InsistentTerminology diplomatic action]]", which, if successful, leads to the city becoming yours. The price depends on city size, buildings within city, wealth of the nation on the receiving end of this treatment, units in city and corruption level (cities owned by democracies have zero corruption and thus cannot be bribed).
* EasyCommunication: As in all the Civ games, you can instantaneously order around everyone in a civilization spanning continents without any communications tech developed. ZigZagged with diplomacy though: By default you loose contact with other nations 20 turns after encountering their units/territory. Without embassies, you can't exchange tech (only sell yours).
* EasyLogistics: Averted big time, in fact, if a unit is based in a city that can't provide for unit upkeep in production points, then units based in said city will die off until the production demands of units equals that of the city's production points. This can cause units wherever they are to simply disappear from the face of the Earth, which is painful if it's a carrier or transport full of units crossing an ocean, or a nuclear missile or stealth bomber that took 5 or more turns to produce.
* EvilIsEasy: Averted. If you don't attack anyone, the AI won't attack you (at least until the endgame) Some AI players will wage war against each other and you can only ally with one party of each war. But your allies (and with wonder-created embassies in each capital all players) will happily exchange tech, pay you for tech and share maps. They don't really get angry at you that fast either: E.g. always making them pay the maximum price for tech will turn them from friendly to neutral at first and to unfriendly quite a while later. You can reconcile relatively easily by just giving them free tech or money or demanding a bit less Gold. They'll often ask you to join their wars, but not doing so at worst lets them cancel their alliance, and most of the time they'll just go from friendly to neutral and forbid you from viewing their map while still ready to trade maps each round.
* FanRemake: Mostly of Civ I and II, but certain features from Civ 3 (like national borders and exchanging cities via diplomacy with other players, only without [[ArtificialStupidity/StrategyGames the AI agreeing to bad deals]]) are also present.
* ForeverWar: AI player often go to war very quickly and then fight for centuries, without either side really winning.
* GameplayAndStoryIntegration: In the Europe scenario map, your civilization starts at the appropriate place of the map. Normally, your settlers also start at a place with terrain typical for your civilization IRL.
* GameplayAutomation: There are build lists that can be applied to new cities so that they automatically construct improvements and troops in the order desired by the player. Cities will also auto-build unless coinage is put in the build queue. Cities can auto-place citizens on tiles/specialist assignments to prioritize Food, Production, Gold, Luxury, Science or Happiness depending on the mayor you choose. Workers, settlers and scouts can be automated as well. You can activate those automations for multiple cities at once from the cities table/tab and by selecting all units of one type.
* GeoEffects: Hills and mountains give a big city defense bonus, woods as smaller one. Rivers, roads and railroads allow units to more farther and give a Trade bonus. Like in Civ, all types of terrain produce specific amounts of Food, Gold and Trade, which can be altered with terrain improvements such as mines, irrigation, farms, fortifications etc.
* GlassCannon: The game manual urges players to escort Catapults and Cannons with units that can defend them.
* GlobalWarming: Each time pollution worsens and global warming advances, the entire world loses coastal land for jungles and swamps, and inland squares are lost to desert. This tends to devastate cities and leads to global impoverishment. Forcing global warming [[http://freeciv.wikia.com/wiki/Global_Warming#Eco-terrorism can be used offensively against other players]].
* HoneyTrap: [[DirtyCommunists Communist nations]] produce spies with an automatic extra experience level.
* HundredPercentAdorationRating / APartyAlsoKnownAsAnOrgy: Like in Civ, cities with very happy citizens (possible with various wonders and buildings that make discontent citizens content and increasing Luxury,boosted by caravan trade routes and various buildings, to make content citizens happy) celebrate and instantly grow irrespective of how full their granaries are.
* ItemAmplifier: Various wonders multiply the effect of city buildings.
* JustOneMoreLevel: Just as bad as the actual Civ games.
* LostTechnology: Huts either give you free tech, gold, free units or barbarians.
* MultipleEndings: You win by either launching the spaceship first, conquering all other countries (except your allies, with whom you can share the win), or having the most points at the end of the last round.
* NecessaryDrawback:
** There are five forms of government: Despotism, Monarchy, Communism, Republic and Democracy. The latter two grant additional trade resources to tiles, the former three grant a number of upkeep-free military units per city making the former more useful for a conquest victory and the latter for a spaceship victory, while making it harder to break alliances with other players, as the senate can veto this. Despotism is what you start with and the least useful, because each tile gets Food and Production penalties. There are also various effects on citizen happiness, corruption levels, wonders, units being bribable or not and celebration/revolt likelihood. Changing the government costs the player one to five rounds of anarchy where basically no resources are gained and nothing is produced.
** There are 6 basic types of units: [[GlassCannon cheap offensive units with very high attack but very low defense]] (e.g. archer, catapult, cannon, artillery, howitzer, submarine), [[LightningBruiser fast but expensive units with high attack and moderate to low defence]] (e.g. horseman, chariot, knight, dragoon, cavalry, armor, paratroopers, helicopter, destroyer, fighter), [[JackOfAllStats expensive units with balanced attack and defense]] (e.g. alpine troops, marines, battleships, AEGIS cruisers, mechanized infantry), [[ZergRush cheap and weak units with balanced attack and defense]] (e.g. partisans, riflemen, warriors), [[CloakAndDagger espionage units]] (e.g. diplomat and spy) and [[SquishyWizard defenseless logistics and support units]] (e.g. trireme, caravel, galleon, transport, AWACS, workers, engineer, settler).
** Each terrain has its properties: Rivers allow faster transport, but Bridge building technology is required to build roads on or across them. Hills and mountains offer extra defense and production points, but allow low mobility and low food points, which is also true for forests. Grassland has high food points and good mobility but low or no production points and no defensive qualities. Wine, Silk, Gems and Gold in hills, forests, jungles and mountains respectively bring high trade but low production points, while vice versa applies in the same biomes for Coal, Pheasants, Fruits (high food instead for Pheasants and Fruits) and Iron. Meanwhile, plains are the {{jack of all stats}} biome with reasonable food and production, good mobility but no defensive qualities. Utilising ocean or lake squares for production and food may offer less than certain land squares, but ocean and lake squares have high trade points (but you can't increase its trade point value) and cannot be polluted or suffer nuclear fallout and thus can be constantly exploited.
** Nuclear missile units can wipe out unlimited numbers of units in the blink of an eye and allow for instant conquest of even the largest cities (assuming that nearby SDI defense buildings or AEGIS cruisers don't shoot down your nuke). However, this pollutes land terrain with nuclear fallout (which can be cleaned up), and can lead to nuclear winter (where large swaths of land become desert, tundra, or worst of all, useless glacier) and the possibility of oceans freezing over (making sea units worthless and harming coastal cities dependent on the ocean for production and food by making them no longer located on the coast).
* NewTechIsNotCheap: The higher the tech level, the more Bulbs (Science points) a tech costs.
* NukeEm: There are [[NukeEm Nuclear (missile) units]]. It may be [[InfinityPlusOneSword very expensive and require much research on the]] {{Tech Tree}} but its attack [[SplashDamage destroys all units within a 3x3 radius]]. It is most often used to clear out cities containing large numbers of defending units, but becomes even more legendary when [[CrowningMomentOfAwesome they can nuke up to 4 cities with one blast]], provided you detonate the nuke between the 4 cities and those cities are all located within a 3x3 area. To discourage [[ILoveNuclearPower liberal use of nukes]], [[VideoGameCrueltyPunishment nuclear winter will start if enough of the world has been hit by nukes]]. Its only weakness is that if your enemies have SDI defense buildings or [[CoolBoat AEGIS cruisers]] near your intended detonation sites, in which case your nuclear unit is shot down and disappears into thin air.
* PerpetualPoverty: Some nations start on remote islands/continents with no production point bearing biomes. They are literally stuck in the Stone Age because they cannot build new units to expand/conquer and because they are unable to produce any form of research. [[TheWoobie Nations in such a terrible situation are almost begging to be put out of their misery]].
* PleaseSelectNewCityName
* PoliticallyCorrectHistory: The civilization descriptions are somewhat glorifying, just like in the Civ games.
* PopularHistory: PlayedStraight withe the wonders, averted with the civilizations, which are far more numerous than in Civ (though the 50 standard civs, pretty much identical to the civs in Civ, play it straight again)
* PyramidPower: The Pyramids grant you the same food bonus as a granary in every city and cumulate with it.
* RandomlyGeneratedLevels
* TechnologyLevels: As standard for ''Civilization'' games, it uses this only to a certain extent. For example, it is perfectly possible to build Ironclad units without having researched Iron Working, and to build and launch a spaceship without ever having discovered Sanitation.
* TheDogBitesBack: Capture the capital of an [[AnarchyIsChaos anarchic state]], there is a 90% chance of {{civil war}}, [[DayOfTheJackboot with despotism]] it is 80%, [[TheEmpire with monarchy]] it is 70%, [[DirtyCommunists with communism]] it is 50%, [[TheRepublic with republic]] it is 40% and [[VideoGameCaringPotential with democracy]] it is 30%. The point is, the harsher your government, the more your people want independence from you once your [[DecapitatedArmy capital is lost]].
** However [[HypocriticalHumour unpleasant it is to have this happen to you]], bear in mind that the same odds apply when you do [[MoralMyopia the same to your enemies]], [[ComedicSociopathy in which case it is satisfying to watch the]] {{enemy civil war}}.
* UndyingLoyalty: [[LaResistance Partisans]] are formed when a city built and owned by a democratic or communist nation is conquered, provided that said nation has discovered gunpowder. The number produced depends on city size, and may be sufficient to reconquer the city. Also, unlike normally produced partisans, those produced by loss of a city have no home city, thus providing soldiers for free without any upkeep costs.
* VastBureaucracy: Represented by the Civ-derived corruption mechanic (cities lose Trade resources), depending on distance from your capital and government type (the more democratic, the less corruption).
* VeteranUnit: Units become veterans via combat experience or Barracks in the city building them them. In the experimental ruleset since v2.4.0, even [[http://gna.org/bugs/?19818 workers can become veterans]] from working experience.
* WeWillHavePerfectHealthInTheFuture: Just like in Civ I, the ''Cure For Cancer'' wonder bestows +1 happiness.
* WorkerUnit: Workers (later engineers) and settlers. The former are commonly used for terrain improvements, roads and railroads, the latter for building new cities, even though they also have all the terrain improvement capabilities.
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