X2: The Threat is a space simulation video game developed by Egosoft for Windows, Linux, and Mac OS X. It is part of the X series. It was released in 2003 and is a sequel to X: Beyond the Frontier. Freeverse Software ported the game to Mac OS X in 2004/2005, while Linux Game Publishing produced their Linux port in 2005/2006. An expansion pack, X2: The Return, was cancelled.

X: Beyond the Frontier is a video game created by Egosoft for Windows. The first of the X series, it is a space trading and combat simulator game, mostly set in the fictional X-Universe. Upon release, it was frequently compared to the older Elite.