L4D2 promises to set a new benchmark for co-operative action games and become one of 2009's marquee titles, adding melee combat to enable deeper co-operative gameplay, with items such as a chainsaw, frying pan, axe, baseball bat, and more.

Released just two weeks ago, over 2 million retails copies of L4D2 have been sold worldwide and the game appears to be on target to become one of the top selling Xbox and PC titles for the month of November. Sales to date are more than double the original title, which was released exactly one year prior to L4D2. And "Black Friday" promotions during the title's second week of availability in North American resulted in stronger than expected sales in L4D2's bid to become one of this year's best selling releases on both platforms.

"Left 4 Dead 2 is off to a great start with strong support at retail and great reviews from the press," said Doug Lombardi, VP of marketing at Valve. "Meanwhile the title has already been played by over 1 million Xbox LIVE Gold account holders, and news regarding L4D2 DLC 1 is coming very soon."   

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.

In addition to the new campaign and boss monster L4D2 also includes "Mudmen," the "uncommon common" exclusive to the Swamp Fever campaign, and a few more of the 20-plus new items coming in the full product (cricket bat, AK47, and grenade launcher).

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.