Left 4 Dead games and expansions must be accompanied by a movie-style poster, according to some law of physics governing development studio Valve Software. The Sacrifice, which is out on October 5 for L4D 1 and 2, now has its own.

The Sacrifice is the newest piece of Left 4 Dead content that bridges Valve's original 2008 multiplayer zombie-shooting game and its 2009 sequel. The Sacrifice stars the heroes of the first game, as they fight toward an encounter with the heroes of the second.

The expansion, which lets players choose which of the L4D leads will die, is free to PC owners of either game and will cost $7 (560 Microsoft points) for Xbox 360 owners. Owners of the original game and the sequel will be able to download The Sacrifice. It includes levels that are playable in campaign, versus and survival modes.