Bill + "ninjah sword" = AWESOME

Via the official Left 4 Dead blog:  

"The Sacrifice” is the prequel to "The Passing," and takes place from the Left 4 Dead Survivors' perspective as they make their way South. You may read the comic to find out the official version of events or this October 5th you may play the game to choose your own ending.

In "The Sacrifice" for Left 4 Dead, gamers receive the complete Sacrifice campaign with maps playable in Campaign, Versus, and Survival. There are 5 new achievements, a new style finale and plenty of places for devastating Hunter pounces.

For Left 4 Dead 2, gamers receive “The Sacrifice” campaign and L4D1’s “No Mercy” both playable with the L4D1 Survivors. This version also offers 5 new achievements. In the L4D2 version of “The Sacrifice” each campaign is playable in Campaign, Versus, Survival, and Scavenge modes, and both "The Sacrifice" and L4D2 version of No Mercy feature the Left 4 Dead 2 Special Infected, items, and weapons. Yes, Zoey with a chainsaw!

"The Sacrifice" will be available as two separate packages on Xbox Live for 560 Microsoft Points each and free to all PC gamers.

Check out the incredibly awesome trailer for it below.



And other cool info (from the above video's description): 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.

After reading all that and watching the trailer, I just popped a boner.