XCOM: Enemy Unknown - Windows

From the award-winning creators of Civilization comes an action-strategy game about civilization's last stand. Threatened by an unknown enemy, the Earth's governments unite to form an elite paramilitary organization, known as XCOM, to combat this extraterrestrial attack. As the commander of XCOM, you control the global defense team in a battle against a terrifying alien invasion by creating a fully operational base, researching alien technologies, planning combat missions, and controlling soldier movement in battle.