Half-Life: Decay
Half-Life: Decay is a multiplayer expansion pack for Half-Life. Created by Gearbox Software and published by Sierra, Decay was released as part of the PlayStation 2 version of Half-Life in 2001. It is the third expansion pack for Half-Life, and like the other expansion packs, Decay returns to the setting and timeline of the original story and portrays the story from the perspective of a different set of protagonists: two female scientists working in the Black Mesa Research Facility. Decay is a cooperative multiplayer game, designed to be played by two people working together to pass through the game's levels.