is an FPS series developed by Valve. The first game, Half-Life, was released in 2000. There has since been many sequels released. Portal and Portal 2 are considered spin-offs of the series, and these games are set in the same universe.
|1999||Half-Life: Opposing Force|
|2001||Half-Life: Blue Shift|
|2006||Half-Life 2: Episode One|
|2007||Half-Life 2: Episode Two|
|TBA||Half-Life 2: Episode Three|