* Next generation co-op action gaming from the makers of Half-Life, Portal, Team Fortress and Counter-Strike. * AI Director 2.0: Advanced technology dubbed "The AI Director" drove L4D"s unique gameplay - customizing enemy population, effects, and music, based upon the players" performance. * L4D 2 features "The AI Director 2.0" which expands the Director"s ability to customize level layout, world objects, weather, and lighting to reflect different times of day. * New melee weapons - axe, chainsaw, frying pan, baseball bat - allow you to get up close with the zombies. * Four different survivors. New Story. New dialogue. * More game. On day one, L4D 2 features more co-operative campaigns, more campaigns and maps for the Versus game modes than L4D, plus support for Survival mode out of the box. * Stats, rankings, and awards system drives collaborative play. * ESRB Rating: MATURE with Blood and Gore, Language, and Intense Violence