Turtle Rock Studios was a video game developer founded in March 2002 by Michael Booth, later acquired by Valve Corporation. Turtle Rock was involved in the creation of original titles as well as the provision of consulting services to the digital entertainment industry.
On November 20 2006, Turtle Rock announced Left 4 Dead, a co-operative multiplayer action game. The game will be built atop the most advanced version of the Source Engine and introduces version 2 of Turtle Rock's AI technology. The game is scheduled to debut on Microsoft Windows and the Xbox 360 in November 2008.
On 10th January 2008, Valve Corporation announced that they had acquired Turtle Rock Studios.