Bent on Humankind's extermination, a powerful fellowship of alien races known as the Covenant is wiping out Earth's fledgling interstellar empire. You and hte other surviving defenders of a devastated colony-world make desperate attempt to lure the alien fleet away from Earth. Shot down and marooned on the ancient ring-world Halo, you begin a guerilla-war against the Covenant. Fight for humanity against an alien onslaught as you race to uncover the mysteries of Halo.

Races
The Human race
The Covenant Race
The Flood
343 Guilty Spark