Left 4 Dead 2

Left 4 Dead 2 is a cooperative first-person shooter video game, the sequel to Turtle Rock Studios's 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. On September 5, 2010 the game was made available to the Steam client for Mac OS X, and on July 2, 2013 it was made available through Steam for Linux.

Left 4 Dead 2 builds upon 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 zombie-like tendencies. The Survivors must fight their way through five campaigns, interspersed with safe houses that act ascheckpoints, with the goal of escape at each campaign's finale. The gameplay is procedurally altered by the "AI Director 2.0", which monitors the players' performance and adjusts the scenario to provide a dynamic challenge. Other new features include new types of Special Infected and an arsenal of melee weapons.