Xulu Universe is a free-to-play, massively multiplayer online physics-based virtual world.
XIII Century Gold
The Gold Edition includes XIII: Death or Glory AND XIII Blood of Europe! Two awesome games for a great price!
Xiah is an Asian-themed martial arts focused MMORPG that supports up to four players and several control schemes.
X-Men Legends II: Rise of Apocalypse
In X-Men Legends II, the X-Men must join their enemy the Brotherhood to fight a greater menace--Apocalypse. The sequel to the team-based role-playing game X-Men Legends lets you play as one of many X-Men, and use and combine his or her unique abilities to defeat enemies.
A competent dungeon crawler marred by some presentation and design shortcomings, Xanadu is a bare-bones action RPG that we recommend only to more forgiving fans of the genre.