Left 4 Dead 2

Left 4 Dead 2 is a 2009 first-person shooter game by Valve. The sequel to Left 4 Dead (2008) and the second game in the Left 4 Dead series, it was released for Windows and Xbox 360 in November 2009, Mac OS X in October 2010, and Linux in July 2013. 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, the game focuses on four new Survivors, fighting against hordes of zombies known as the Infected, who develop severe psychosis and act extremely aggressive.