Left 4 Dead 2

Left 4 Dead 2 adds melee combat to enable deeper co-operative gameplay, with items such as a chainsaw, frying pan, axe, baseball bat, and more.

Introducing the AI Director 2.0, L4D's dynamic gameplay is taken to the next level by giving the Director the ability to procedurally change weather effects, world objects, and pathways in addition to tailoring the enemy population, effects, and sounds to match the players' performance. The result is a unique game session custom fitted to provide a satisfying and uniquely challenging experience each time the game is played.

Featuring new Survivors, boss zombies, weapons, and items, Left 4 Dead 2 offers a much larger game than the original with more co-operative campaigns, more Versus campaigns, and maps for Survival mode available at launch.

system requirements:
Core 2 Duo 2.4 GHz, 1 GB RAM, graphic card GeForce 7600 or better, 7.5 GB HDD, Windows XP/Vista/7.

http://www.ourpcgame.net/2009/07/left-4-dead-2.html