-> ''[[FourXGame TRADE. FIGHT. BUILD. THINK.]]''

A WideOpenSandbox singleplayer [[SimulationGame space combat]]/[[FourX trading and empire management simulator]] series by German developer Egosoft.

The series (the "''X-Universe''") contains:
* ''VideoGame/XBeyondTheFrontier'', (1999)
** ''X-Tension'', (2000, expansion for ''X: BTF'')
* ''X2: The Threat'', (2003)
* ''X3: Reunion'', (2005)
** ''X3: Terran Conflict'' (2008); standalone expansion pack for ''Reunion''
*** ''X3: Albion Prelude'' (2011); expansion pack for ''Terran Conflict''
* ''Videogame/XRebirth'' (2013); soft reboot of the series
* ''X4: Foundations'' (2018 or 2019)

The series does have an overall plot and extensive backstory but most players find it to be far outshined by the WideOpenSandbox empire-building aspect. For that reason, the plot summary is [[Synopsis/{{X}} on another page]]. In ''X'' you can just play through the plot, content to stay in your puny little [[SpaceFighter fighter]] or [[SpaceTrucker freighter]] and not straying much farther than your starting sector, or you can create a [[NGOSuperPower universe-spanning trading empire, all but controlling the economy and with enough military power to squash all who dare oppose you]]. You can also do things that you're not really meant to do, such as almost completely [[OmnicidalNeutral wiping out a race from the universe]]. It takes a hell of a lot of military resources, and it'll probably break the economy unless you supply it with that race's goods yourself, but nobody's actively ''stopping'' you from doing it. The only reason you can't destroy ''everything'' is because the game engine tries to keep the economy balanced and will slowly recreate destroyed stations if need be.

The series from ''X-Tension'' and beyond - with a notable exception in ''Rebirth'', which caused a massive BrokenBase - allows the player to [[UniversalDriversLicense pilot almost anything they can see]], from tiny scout ships to [[MileLongShip five kilometer long destroyers and carriers]]. There are many classes of ships - [[StandardSciFiFleet fighters, carriers, corvettes, bombers, freighters]], etc - and each race has their own ship set with their own unique advantages and disadvantages. [[PlayerMooks Player-owned ships]] can be commanded to perform tasks, such as patrolling, exploring, or trading.

The economy is an important aspect to the games -- the only wares that are generated without resources are energy cells, and ships at shipyards[[note]]Ships built by the player, however, have resource and time requirements[[/note]]. Everything else requires RefiningResources to produce. A satellite factory, for example, may require energy, processed food, and microchips to produce satellites.

Unlike other games, the economy will go gleefully on without the player's intervention. Trading ships will carry wares between stations to make profit, much like the player would - making them competition. New stations will (slowly) be built in systems, and some stations may be lost to [[SpacePirate pirate attacks]], which can cripple the economy. The player can patch holes in the economy by building their ''own'' space stations, or completely overtake the entire economy of a race by flooding it with cheap goods.

The games all have extensive support for {{Game Mod}}s.


In mid-2011 Egosoft announced a revamp of the series via the next main series game, ''VideoGame/XRebirth'', due out November 2013. To the fanbase's rather abrupt surprise, they then announced a new "expandalone" game using the ''X3: Terran Conflict'' engine, ''Albion Prelude'', mere days before its surprise release date. Named after the ship that is the focus of ''X: Rebirth'', ''Albion'' adds a Stock Exchange to the game, as well as progressing the story to the massive interstellar war that was brewing by the end of ''X3: Terran Conflict''.

On August 26, 2017, Egosoft officially announces X4, which will be set after ''X3'' and ''VideoGame/XRebirth''. Running on an updated ''Rebirth'' engine, it restores most of the features from the previous games such as being able to pilot every ship.

The series also features several tie-in novels written by Helge T. Kautz, though only ''Dominion'', ''Rogue'', and ''Farnham's Legend'' are currently available in English.

[[JustForFun/IThoughtThatWas Not to be confused with]] ''Manga/{{X 1999}}'', ''X'' the Nintendo tank game, the punk band Music/{{X}}, the ''Franchise/XMen'' (especially with the sequels of the movie getting called [[NamesTheSame X2 and X3]] [[FanNickname by fans]]), or ''VideoGame/MegaManX''. Has nothing to do with ''VideoGame/{{XCOM}}'' or ''VideoGame/{{Xenoblade Chronicles X}}''.


Now divided into subpages.

* Tropes applying to the X-Universe setting as a whole:
** XUniverse/Tropes0ToF
** XUniverse/TropesGToL
** XUniverse/TropesMToR
** XUniverse/TropesSToZ

* Tropes specific to particular games:
** ''VideoGame/XBeyondTheFrontier''
** ''VideoGame/XRebirth''