X³: Reunion is a space trading and combat simulation that continues the story of X²: The Threat. The war with the mysterious Khaak still rages at the borders of Argon space, where the weakened defending forces try to stop the expanding invasion. But a new, even bigger menace arises in the endless darkness of space.
Like its predecessors, the game features free-form gameplay, allowing the player to completely ignore the main story of the game (actually there is an option to play the game without any story at all). There are several ways to earn money or reputation - mining asteroids, trading, building player-owned stations, fighting against pirates or becoming pirate oneself, and so on. only to name a few. With a large variety of ships and equipment, the player can build (or capture) a whole customized battle and/or trading fleet.
The X²: The Threat expansion X²: The Return (German title: X²: Die Rückkehr) was canceled near completion to take advantage of the X³ engine. All of the expansion's content was integrated into this game.