Valve is debuting a new title at this year's show, Left 4 Dead 2 -- the sequel to last year's best selling and critically acclaimed cooperative action game.

Left 4 Dead was something of a surprise success last year, capturing the attention of enough PC and Xbox 360 gamers for it to become the number one selling new game IP on both platforms. Targeted for release on those same platforms on November 17 (the one year anniversary of L4D and 11 year anniversary of Half-Life 1), Left 4 Dead 2 promises to become one of this year's best selling titles.

Set in the Deep South, L4D2 casts players as one of four new Survivors: a news intern, a football coach, a mechanic and a riverboat gambler. These four meet just as the Zombie Apocalypse is hitting their city. just after the viral outbreak that has turned most of the population into a variety of mutant zombies.

One of the things that made Left 4 Dead's gameplay successful was a set of technologies dubbed "The AI Director" which custom-tailored the enemy population, effects and music based upon the player's performance. L4D2 introduces the AI Director 2.0 and takes the gameplay 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.

L4D2 also introduces melee combat with items such as a chainsaw, frying pan, axe, baseball bat, and more. In addition to the melee combat items, the game introduces new firearms and special ammo such as incendiary ammo. Here at the show we will be showing off "The Parish," one of the five new campaigns shipping with the game this November. All five of L4D2's co-operative campaigns will support Versus and Survival mode at launch. The other four campaigns will be revealed between now and launch.

It's also worth noting that L4D2 will be supported with an even more aggressive advertising campaign than the original. Folks can expect to see even more of "the hand" on TV, online and the billboards in train stations and roadsides. And, like the original, L4D2 is available for pre-order at a $5 discount plus early access to the official demo (on Steam and at participating retailers).

E3 will be the start of an interesting and fun campaign. More importantly, we hope everyone enjoys the game!