Valve Corporation is an American video game development and digital distribution company based in Bellevue, Washington, U.S. that was founded in 1996, and made famous by its first product, Half-Life, which was released in November 1998, and by its distribution software, Steam. They are known for their first-person shooters, and long development cycles.

They acquired the team who worked on the original Alien Swarm total conversion mod for Unreal Tournament 2004, and the released Alien Swarm using the Source engine.

Famous games from Valve include: The Half Life Series, Portal, Left 4 Dead, Counter Strike, Day of Defeat and the Team Fortress series.

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