The '''4X''' video game genre is a sub-genre of the strategy genre. The name comes from the 4 "X"'s that comprise a summary of the genre's gameplay:

* '''X'''-Plore: Look around and find interesting things.
* '''X'''-Pand: [[SettlingTheFrontier Build more cities/colonies/space stations on the territory you just found]].
* '''X'''-Ploit: Improve the cities/colonies/space stations through various means, making the most of the resources you have acquired.
* '''X'''-Terminate: Use those resources to [[KillEmAll kill everyone who isn't you]] and take their stuff.

Technically, it should be 4 ''E'', but [[XtremeKoolLetterz the "X"]] [[XMakesAnythingCool just sounds cooler]].

In 4X games, you control an empire that is in competition with other empires. These "empires" can represent different [[TheClan clans]], tribes or cultures, or even different alien races. Different empires may also have different advantages or disadvantages; some games even allow you to create customized empires on your own.

The empires will be competing over a region that could be as small as England, or as large as the Galaxy. Most members of the genre do not require that you play them on a specific piece of terrain. Instead, most of them offer a randomized map generator, typically with settings that affect the outcome (how many planets, how much water vs. land on Earth-like worlds, etc). The map almost always features some degree of FogOfWar, requiring the player to devote resources to e'''x'''plore the map in order to discover new resources to e'''x'''ploit.

On whatever map the player chooses, there are territories on which you can build "cities" (whether planetary colonies, space stations, or just cities). Cities e'''x'''ploit the resources in the region where they are built, and can transform those resources into "buildings" (improvements to the city's efficiency), money, or units.

Units can move various distances on the map, possibly with terrain restrictions, and perform a variety of tasks -- which may or may not include combat. You almost always have to produce a special type of unit that can create another city to let you e'''x'''pand your empire. Some games allow you to create customized units based on your technology base (see below), in addition to the default units included in the game.

Other empires work under the same restrictions as you (except when they are [[TheComputerIsACheatingBastard cheating bastards]]). You can talk to other empires, broker peace with them, trade with them, ally with them against a common foe, or kill them. Mostly kill them. Be careful: they will do the same to you, and [[RelationshipValues they will remember what you've done to them]].

Most 4X games feature a TechTree, though others may use TechnologyLevels instead; some even combine the two. Cities produce research, which is used to research new technologies. The Tech Tree is so named because you cannot research a technology until you have its prerequisites. You can't learn "Alphabet" until you've learned "Writing", for example. Technologies provide upgrades for cities, letting you better use their resources, build new units, buildings, or weapons, and so forth.

A staple of the genre, borrowed from the originator of the genre ''VideoGame/{{Civilization}}'', is the "Wonder". It is a city-produced construct that only one city in the entire game-world can produce. Whichever empire builds it first gets its benefits, and everyone else gets zilch. It generally confers a substantial benefit to the civilization that produced it, and it can only change hands if the city it is built in changes hands. More recent 4X games offer less powerful non-global "Wonders" that each empire can build, but can only be built in one of their cities. These typically provide a large bonus to a specific city.

One other staple originated by ''Civilization'' is the "goodie hut"; random local tribes/lost cargo pods/space anomalies that act as InexplicableTreasureChests for the first player to discover them. Of course, some of them can act as [[ChestMonster Chest Monsters]], as well...

Just to make sure you can't be completely pacifist, you will usually encounter {{barbarian tribe}}s (pirates/guerrillas/terrorists/angry alien fungi) that appear out of nowhere and cannot be negotiated with (although their units may be captured instead of destroyed if the player is clever).

Victory in 4X games will always be available by e'''x'''terminating all or most of your opposition. However, 4X games are usually expected to offer one or more alternative victory conditions. Some allow you to pool your civilization's production in order to produce a gigantic monument, such as ''Civilization's'' [[SidMeiersAlphaCentauri UN Unity Spaceship]], or ''Alpha Centauri's'' [[AscendToAHigherPlaneOfExistence Ascent to Transcendence]]. If you can do that, spending all of those resources while defending your borders from people trying to stop you, you win. In some games, researching a long series of technologies (typically that do not provide any immediate benefit) causes victory. If you ally with all other (surviving) empires, then you win in some games. While all victory conditions are usually open to all players, [[VariablePlayerGoals some factions are often more suited to pursuing certain endgames than others]].

Historical versions of the genre tend towards allowing AnachronismStew, but at the direction of the player. A player's civilization might reach tanks and battleships by 1000 AD while the computer players are still in the iron age or develop genetic engineering before electricity. Futuristic versions tend to use a lot of TechnoBabble in their unit/weapon/technology names and descriptions.

Gameplay is usually either [[RealTimeStrategy real-time]] or [[TurnBasedStrategy turn-based]]. ''Sid Meier's VideoGame/{{Civilization}}'' is one of most famous exemplars of the latter, while probably the best-known of the former is the ''VideoGame/AgeOfEmpires'' series.

Not to be confused with either a popular Australian brand of beer, the stand-in continent for Australia in ''Literature/{{Discworld}}'', '''[[{{Squick}} extreme]]''' pornography (XXXX) or the [[RidiculousExchangeRates Foreign Exchange Market]].

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[[index]]

[[folder:Tabletop Games]]
* As noted below, Creator/AvalonHill's ''Civilization'' served as an inspiration for Sid Meier's video game of the same name.
* Creator/FantasyFlightGames brought out a [[RecursiveAdaptation board game version]] of ''Sid Meier's Civilization'' in 2010, designed by Kevin Wilson. The game remains mostly faithful to its PC counterpart, with production, research, combat, multiple victory conditions and a hidden map to explore, while condensing the whole experience to around 4 hours.
** ''TabletopGame/TwilightImperium'' is basically ''Master of Orion'' as a boardgame.
[[/folder]]

[[folder:Video Games]]
* ''VideoGame/AgeOfEmpires'' is a RealTimeStrategy variation.
* ''VideoGame/AgeOfWonders'', a SpiritualSuccessor to ''VideoGame/MasterOfMagic''.
%%* ''VideoGame/{{Armada 2526}}''
* ''VideoGame/{{Ascendancy}}'' was a game that let you control your species from the individual-planet-level project to managing the entire empire of star systems. It featured no less than twenty-one species, each with a different special ability - and humans aren't one of them.
* ''VideoGame/Aurora4X'' is a freeware 4X space game, and is considered the ''VideoGame/DwarfFortress'' of 4X games. it is notable for its expansiveness and unintuitive user interface (like ''Dwarf Fortress'') and may be one of the most complicated space 4X games ever created. The game is more like a series of spreadsheets and drop-down lists than an actual game. Planets are generated with tectonics and ecosystems, ships must be carefully crafted with much thought put into the targeting and guidance systems as well as a whole plethora of minute details, armies and civilizations can be determined down to the individual person, needless to say this game is VERY detailed. It's [[http://aurora2.pentarch.org/ available here]].
%%* ''VideoGame/CastlesSiegeAndConquest'' is a simple, somewhat realtime [=4X=] game in which you compete with other lords for rulership of France using guile and diplomacy after the king dies without issue. Once you claim the throne, expect even your closest allies to immediately turn on you.
* The ''VideoGame/{{Civilization}}'' series [[UrExample invented]], [[TropeMaker refined]] or [[TropeCodifier codified]] most of the tropes of this genre. It allows the player to shepherd a civilization through Earth's history. It was originally based on a board game by Creator/AvalonHill that allowed you to play from the Stone Age to the Roman Empire era.
** ''VideoGame/FallFromHeaven'' is one of the more well-known ''Civilization'' {{Game Mod}}s.
* ''VideoGame/{{Colonization}}'' is Civilization [[RecycledInSpace in America!]] Though it has some significant differences: no tech tree, and most units are very, very specialized. Also, Wonders are replaced by "Founding Fathers" ([[AndZoidberg plus Pocahontas]].)
* ''VideoGame/CivilizationCallToPower'' is an [[InNameOnly in-name-only]] ''VideoGame/{{Civilization}}'' game/spin-off which features similar gameplay to ''Civilization II'' along with its own unique gameplay features. It also had units which didn't appear in the ''Civilization'' series proper, such as [[ArmyOfLawyers lawyers]] and [[HumongousMecha mecha]], until much later.
* ''VideoGame/CivilizationBeyondEarth'', spin-off of ''Civilization V'' and SpiritualSuccessor to ''Videogame/SidMeiersAlphaCentauri''.
* ''VideoGame/CrusaderKings''
* ''{{Deadlock}}'' and its successor ''Deadlock II'' had different races fighting over a series of planets within a "Dark Cloud". The original game had only one planet; in the sequel, the races discovered that there was actually a series of planets further in, all formerly owned by a mysterious ancient race. The plot revolved around finding the technologies and temples left behind by this ancient race.
* ''VideoGame/DistantWorlds''
* ''VideoGame/ElementalWarOfMagic'', a SpiritualSuccessor to ''VideoGame/MasterOfMagic''.
%%* ''VideoGame/{{Empire}}'' (a.k.a. ''Classic Empire'')
* ''VideoGame/EndlessSpace''
* The ''VideoGame/{{Dominions}}'' trilogy revolves around various entities attempting to achieve godhood through the expedient method of wiping out all competition.
* ''VideoGame/EuropaUniversalis''
* ''VideoGame/FreeCiv'' is a very customizable ''VideoGame/{{Civilization}}'' clone.
* ''VideoGame/GalacticCivilizations'' and its sequel, ''[=GalCiv=] 2''.
* ''VideoGame/GihrensGreed'' is a FourX game based on ''Franchise/{{Gundam}}'', specifically the Universal Century continuity.
* ''VideoGame/HaegemoniaLegionsOfIron'': SpiritualSuccessor to ''Imperium Galactica II'' and borrows heavily from ''VideoGame/MasterOfOrion'' and ''VideoGame/{{Homeworld}}''.
%%* ''VideoGame/{{Imperialism}}'' might be called a "3.5X": the entire map is visible at the start, but the player must build specialized units to see if there is [[MemeticMutation gold in them thar hills.]] (Or iron, or coal, or diamonds.)
* ''VideoGame/ImperiumGalactica'' and its sequel.
* ''VideoGame/TheKingOfDragonPass'' is a strange example including lots of [[RolePlayingGame RPG]] and VisualNovel elements.
* ''VideoGame/LightOfAltair'', a welcoming, simplified indie title.
* ''VideoGame/MasterOfMagic'', a fantasy-themed spinoff of ''Master of Orion'', below.
* The term "4X" was coined in a review of the first installment of the ''VideoGame/MasterOfOrion'' series. ''Master of Orion 3'' riffed off this by including "The X's" as actual {{MacGuffin}}s within the game, including a semi-mythical "5th X".
* ''VideoGame/NeptunesPride'' and its sequel, ''Triton'', are browser-based free-to-play 4X games. They're played in real time, but very slowly, with travel times between stars measured in hours and resources paid out once per day. A typical game lasts from a few weeks to a month or more.
%%* ''VideoGame/ReachForTheStars''
* ''VideoGame/PandoraFirstContact'' is a 4x game, made as a spiritual successor to VideoGame/SidMeiersAlphaCentauri
* ''VideoGame/RiseOfNations'', created when its developers realized they wanted a RealTime ''Civilization'' game.[[labelnote:*]]Just to be clear, that means you can go from throwing sticks to nuclear bombers in half an hour, not that it takes 5000 years to play a game.[[/labelnote]] It's an RTS with a RiskStyleMap, but covers a lot of the same ground.
** ''VideoGame/RiseOfLegends'' is its sequel, using a similar resource and map system, but instead of real-world civilizations it has a three-sided war between SteamPunk Italian city-states, Literature/ArabianNights-style desert nomad magicians, and South Americans led by AncientAstronauts.
* ''VideoGame/ShoresOfHazeron'' is a MMO FourX played from the first person perspective.
* ''Videogame/SidMeiersAlphaCentauri'' is the [[SpiritualSuccessor spiritual "sequel"]] to ''Civilization'' [-[[RecycledInSpace IN SPACE!]]-]. The game's tagline is "Explore. Discover. Build. Conquer." They even managed to integrate that into the gameplay on a second level: Technologies are divided into types (Explore=scout/exploration/environmental technologies, Discover=pure science, Build=industrial technologies, Conquer=military tech) and a player can have the AI "Governor" of any given base focus on one or more tracks if he/she doesn't care for micromanaging.
** This game is also a bit rare among 4Xs for having a general plot. Through quotes when you construct structures, research technologies, and complete projects(Wonders), a loosely connected story is told, and a {{Canon}} game progression is hinted at.
* ''VideoGame/SinsOfASolarEmpire'' is a spacegoing RealTimeStrategy game with shades of [=4X=].
* ''VideoGame/SpacewardHo'' is an interstellar 4X game with a Western theme.
* ''VideoGame/SpaceEmpires'', a series of highly-customizable 4X games with such an extensive system of micromanagement as to make the micromanagement need in the ''Civ'' games pale in comparison.
* ''VideoGame/{{Spore}}'' plays like one of these during the Tribal and Civilization Stages of the game.
* ''VideoGame/StarbaseOrion'' started off as an [[IOSGames iOS]] port for ''Master of Orion'' but has evolved since then.
* ''Videogame/StarDrive'' is a realtime example.
%%* ''VideoGame/{{Stars}}''
* ''VideoGame/StarRuler'' is another RealTimeStrategy take.
* ''VideoGame/SwordOfTheStars'': Turn-based on the strategic level, real-time on the tactical level. The intro even mentions two of the "x"s by name (and uses "conquer" instead of the last).
%%* ''VideoGame/VGAPlanets''
* ''VideoGame/VictoriaAnEmpireUnderTheSun''
* The ''VideoGame/{{X}}-Universe'' series is a real time space simulation like ''VideoGame/{{Elite}}'' that revolves around MegaCorp management. The series' motto: "Trade. Fight. Build. Think."
* ''[[VideoGame/XCom X-COM: UFO Defense]]'' combines FourX base-building and RealTimeWithPause interception missions with turn-based tactical battles. ''Terror from the Deep'' and ''Apocalypse'' follow in this trend (though ''Apocalypse'' modifies it significantly); ''Interceptor'', ''Enforcer'' and the 2K Marin version abandon this.
** ''VideoGame/XCOMEnemyUnknown'' returns to the tradition.
[[/folder]]
[[/index]]

[[folder:Other]]
* The board/computer game ''Empire'' that is the source of the Wopuld family's wealth in Creator/IainBanks' ''The Steep Approach to Garbadale'' is a particularly complicated one of these. A similar game: ''Despot'' features in his earlier novel ''Complicity''. The author might just be a fan of the genre.
* The ''Solar Empires'' series of video games in Austin Grossman's ''{{Literature/You}}'' are 4X games (among other things.) The term itself is dropped in the text.
[[/folder]]
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