Left 4 Dead 2 (abbreviated as L4D2) is a cooperative first-person shooter video game and the sequel to Valve Corporation's award-winning Left 4 Dead. The game launched on November 17, 2009, for Microsoft Windows and Xbox 360 in the United States and November 20 in Europe; in 2010, Left 4 Dead 2 was made available to the Steam client for Mac OS X. It builds upon the cooperatively-focused gameplay and Valve's proprietary Source engine, the same game engine used in the original Left 4 Dead. Set during the aftermath of an apocalyptic pandemic, Left 4 Dead 2 focuses on four new Survivors, fighting against hordes of the Infected, who develop severe psychosis and exhibit z ... Read more »