XCOM: Enemy Unknown puts the player in control of an elite multinational paramilitary organization called XCOM tasked with defending Earth from aliens. The player commands troops in the field in a series of turn-based tactical missions; between missions, the player directs the research and development of new technologies from recovered alien technology and captured prisoners, expands XCOM's base of operations, manages XCOM's finances, and monitors and responds to alien activity. (wikipedia.org)