Valve is an entertainment software and technology company founded in 1996 and based in Bellevue, Washington. The company’s debut title, Half-Life, has won over 50 Game of the Year Awards and was named "Best PC Game Ever" in the November 1999, October 2001, and April 2005 issues of PC Gamer, the world's best-selling PC games magazine.

Valve’s portfolio of entertainment titles also includes Counter-Strike™, Day of Defeat™, and Team Fortress®. This portfolio of titles accounts for over 18 million retail units sold worldwide, and Valve games account for over 88% of the PC online action market. In addition to producing best selling entertainment titles, Valve is a developer of leading-edge technologies, such as the Source™ game engine and Steam, a broadband platform for the delivery and management of digital content.

Below is a listing of all the games they have developed and part developed.

Counter-Strike		Day of Defeat		Portal		Team Fortress 2		Left 4 Dead

Half-Life Half-Life: Opposing Force Half-Life: Blue Shift Half-Life: Source Deathmatch Classic Team Fortress Classic Ricochet

Half-Life 2 Half-Life 2: Deathmatch Half-Life 2: Lost Coast Half-Life 2: Episode One Half-Life 2: Episode Two Half-Life 2: Episode Three