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.

"The Sacrifice" is the prequel to "The Passing," and takes place from the L4D Survivors' perspective as they make their way South. In addition to advancing the story, "The Sacrifice" introduces a new style finale featuring "Sacrificial Gameplay" where players get to decide who will give their life so the others may live.

The Sacrifice DLC for L4D1 is a seperate download than The Sacrifice for L4D2.

In The Sacrifice for Left 4 Dead 1 gamers receive the complete Sacrifice campaign with maps playable in Campaign, Versus, and Survival.

In The Sacrifice for Left 4 Dead 2 owners receive "The Sacrifice" campaign playable with the Left 4 Dead  Survivors. In addition, those with Left 4 Dead 2 receive L4D's "No Mercy" campaign. Both campaigns are playable in Campaign, Versus, Survival, and Scavenge modes and both will feature the Left 4 Dead 2 Special Infected, items, and weapons. Yes, Zoey with a chainsaw!

Targeted for release on October 5th, "The Sacrifice" will be available for download on Xbox Live for 560 Microsoft Points and free to all PC gamers.

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.