Valve has snapped up Left 4 Dead (PC, X360) developer Turtle Rock Studios, the company announced today.

The studio, responsible for parts of Counter-Strike: Condition Zero and various Counter-Strike: Source maps, will remain in Orange County, California.

"We have been seeing very strong growth with Steam and Source, our content distribution and development platforms, up over 150% over the last 12 months. Given our expectations for Left 4 Dead and our long-standing relationships with members of the Turtle Rock team, this was an easy decision. It also gives us a base from which to expand our development activities in the Los Angeles area," said Gabe Newell, president of Valve.

Added Turtle Rock Studios CEO Michael Booth, "Valve has had great success bringing in projects and teams such as Team Fortress and Portal. As I spent time working and talking with the creators of those products over the past several years, it became clear that this was the right next step for myself, my colleagues at Turtle Rock, our customers, and our products."