First Alien War

AW-I was a war fought between X-COM forces and a number of invading alien races. Starting with animal mutilations and intermittent human abductions, alien activity steadily escalated, eventually threatening the continued existence of humanity. Striking from hidden bases throughout the world, X-COM soldiers managed to maintain some semblance of order, keeping the alien menace in check until the invaders' base of operations could be located. In a final, cataclysmic battle, a squadron of X-COM soldiers invaded the aliens' base at Cydonia on Mars, killing all the inhabitants and neutralizing the central Brain that controlled the alien invasion force.