Valve Software recently revealed that the next piece of downloadable content (DLC) for its pair of cooperative zombie shooters, Left 4 Dead 1 and 2, will become available early next month (and early next week) for both Xbox 360 and PC players.

Entitled ‘The Sacrifice,’ this DLC is a prequel to the events that occur in Left 4 Dead 2’s DLC, The Passing, and will this time allow you to play as the survivors from the original Left 4 Dead.

The Sacrifice will include a new feature called ‘Sacrificial Gameplay,’ which will task players with deciding who lives or dies, and thus who will go on to fight in the next round. This dynamic has been introduced as a “new style finale” and to add an extra twist to the game.

In addition to The Sacrifice, Left 4 Dead 2 players will get the ‘No Mercy’ campaign from the original Left 4 Dead for use in the sequel, for free, as well as Versus, Survival and Scavenge game modes (over and above the normal Campaign mode).

If you’re an Xbox 360 Left 4 Dead 1/2 gamer, you’ll need to buy The Sacrifice for 560 MS Points, but if you play your Left 4 Dead 1/2 on PC, you’ll be able to get it for free.

Oh, and that release date? October 5th is when The Sacrifice will go live for both Xbox 360 and PC gamers.