Half-Life: Decay

Half-Life: Decay is an add-on included in the PlayStation 2 port of Half-Life, published in 2001. A PC version of this game was released September 23, 2008, developed and released by independent Ukrainian developers with the help of other European developers/fans.

Like Gearbox's other expansion packs Opposing Force and Blue Shift, Decay returns to the setting and timeline of the original story, but with different player characters: two female colleagues of Gordon Freeman, named Gina Cross and Colette Green. Dr. Cross is the model for the Hazard Course hologram and can be seen at a point in Blue Shift. Dr. Green is a new character invented for Decay.

Dr. Cross and Dr. Green are members of a different team in Black Mesa than Half-Life's protagonist, Gordon Freeman. They are responsible for monitoring the equipment which Gordon uses during the experiment, and are in turn monitored by Dr. Rosenberg and Dr. Keller. Like Freeman, they are forced to fight for survival in the aftermath of the Resonance Cascade.