Valve, creators of best-selling game franchises (such as Half-Life and Counter-Strike) and leading technologies (such as Steam and Source), today announced the availability of the Left 4 Dead 2 demo to all PC gamers via Steam.

The Left 4 Dead 2 demo features gameplay taken from "The Parish" campaign, set in the New Orleans French Quarter. Playable by 1 to 4 players over local or Internet connections, the demo features all the new boss infected zombies and many of the new melee weapons included in the full product.

L4D2 promises to set a new benchmark for co-operative action games and become one of 2009's marquee titles. Set for release on November 17, the title adds melee combat to enable deeper co-operative gameplay, with items such as a chainsaws, frying pans, axes, baseball bats, and more.

With 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.

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