XCOM: Enemy Unknown
The developer of the Civilization franchise takes a shot at another cherished strategy series.
Xenoblade Chronicles is a role-playing game which takes place on an immense game world on the remains of two giant titans.
X3: Albion Prelude
X3: Albion Prelude plays in a time between the old and the new X Universe.
X-Men Destiny is an action role-playing game in which you control the fate of a new mutant in the X-Men universe.