Development on the game was completed on November 13, 2008, and two versions were released digitally: A downloadable digital version, released on November 17, 2008, and a digital retail disc version, with a release date determined by region. The game uses Valve's proprietary Source engine, and is available for Microsoft Windows, Xbox 360 and Mac OS X.
It was developed by Turtle Rock Studios, which was purchased by Valve Corporation during development. Left 4 Dead (abbreviated as L4D) is a cooperative first-person shooter arcade-style video game.
