Half-Life: Decay is an add-on for an adventure shooter with a first-person view, released specifically for the PlayStation 2 game console. The game is designed to be played together with another player in split-screen mode. The events of the game take place parallel to the story told in the original, but now you will play the role of research assistants Gina Cross and Colette Greene. You have to understand the incident and fight for your life after a cascading resonance.