Halo: Combat Evolved, or simply Halo, is a science fiction first-person shooter video game developed by Bungie, and first game of the Halo series. It was released on November 15, 2001 as a launch title for the Xbox gaming system, and is considered that platform's "killer application". With more than six million copies sold worldwide, Halo is second only to its sequel, Halo 2, in sales for the Xbox video game console. The game was later ported to Windows and Mac OS.

The titular Halo is an enormous, ring-shaped artificial space habitat, and, according to Bungie, has a diameter of either ten thousand kilometers or miles. Halo sits at a lagrange point between a planet and its moon; this arrangement gives the station rotational gravity. In the game, the player assumes the role of the Master Chief, a cyborg "super-soldier" with battle armor. The Master Chief is accompanied by Cortana, an artificial intelligence who occupies the neural implant between the battle armor and the Master Chief's brain. Players battle various types of aliens on foot or in vehicles as they attempt to uncover the secrets of the Halo. The game has been called "easy to learn," and has been praised for its "engaging story". (more...)