 " The Last Voyage of the Infinite Succor " takes place during and after the sixth mission of the video game Halo : Combat Evolved . During the game , players discover that the ringworld on which they are trapped , dubbed " Halo " by the enemy alien collective the Covenant , is in fact a super weapon designed to wipe out all life in the galaxy to deprive an intergalactic parasite known as the Flood of their food source ( their food source being all sentient life in the galaxy ) . The Flood are accidentally released by the Covenant from stasis and begins to spread across the ring . Halo was built by an ancient alien race known as the Forerunners to contain and study the Flood , but also as a weapon of last resort ; faced with the prospect of the Flood consuming every thinking being in the universe , the Forerunners activated Halo , destroying themselves but also starving the Flood . 
