The first game in the Portal series, set in the same universe as Half-Life, was released in 2007. It was followed by the extra level Lost Coast (2005) and the episodic sequels Episode One (2006) and Episode Two (2007). In 2004, Valve released Half-Life 2 to further success, with a new setting and characters and physics-based gameplay. Half-Life was followed by the expansions Opposing Force (1999), Blue Shift (2001) and Decay (2001), developed by Gearbox Software. The innovative scripted sequences were influential on the FPS genre, and the game inspired numerous community-developed mods, including the multiplayer games Counter-Strike and Day of Defeat. Players control Gordon Freeman, a scientist who must survive an alien invasion.
The original Half-Life, Valve's first product, was released in 1998 for Windows to critical and commercial success. The games combine shooting combat, puzzles and storytelling. Half-Life is a series of first-person shooter (FPS) games developed and published by Valve.
