X³: Reunion is a single-player space trading and combat game developed by Egosoft and published by Deep Silver. It is the third installment in the X universe adventure video game series and the sequel to X²: The Threat (2003), which in turn followed X: Beyond the Frontier (1999). X³: Reunion was released on October 28, 2005 for Windows PCs, Linux and Mac OS X and on November 4, 2005 in North America. The game has been ported to Linux and Mac OS X; Mac OS X for release in August 2007; the Linux version followed on December 5 2008. The X series is often compared to the classic Elite, in that these first-person space adventure games focus on trade and exploration, as well as combat.