The game uses Valve's proprietary Source engine, and is available for Microsoft Windows, Xbox 360 and OS X. 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.
Ang laro ay gumagamit naNg proprietary Source engine na Valve, at available para sa Microsoft Windows, Xbox 360 at OS X. Ang pag-unlad sa laro ay nakumpleto noong Nobyembre 13, 2008, at dalawang bersyon ay inilabas digital: Isang nada-download na digital na bersyon, na inilabas noong Nobyembre 17, 2008, at isang digital na bersyon ng disc retail, na may petsa ng paglabas na tinutukoy ng rehiyon.WikiMatrix WikiMatrix