Left 4 Dead

Left 4 Dead(abbreviated as L4D) is a cooperative first-person shooter arcade-style video game. It was developed by Turlte Rock Studios, which was purchased by Valve Corporation during development. The game uses Valves's proprietary Source engine, and is available for Microsoft Windows, Xbox 360 and Mac 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. The detail retail disc version was released in North America and Australia on November 18, 2008; and in Europe and Japan on November 21, 2008.

Set during the afternath of an apocalyptic pandemic, the game pits its four protagonists- dubbed the "Survivors" -against hordes of the infected.There are four games modes: a single-player mode in which allied characters are controlled by AI; a four player, co-op campaign mode; an eight-player online versus mode; and a four-player survival mode.In all modes, an artificial intelligence (AI), dubbed the "Director", controls level pacing and item replacements, in an attempt to create a dynamic experience and increases replay valve.