Both Left 4 Dead games making The Sacrifice Oct. 5

In April, Valve released the first add-on to its critical hit survival horror zombie shooter Left 4 Dead 2, titled The Passing. Free for PC gamers and 560 Microsoft points ($7) on the Xbox 360, The Passing offered a connection between the events of the original Left 4 Dead and its 2009 sequel, as the games' casts teamed up to battle their way through the teaming hordes.

Today, Valve provided a date for its next round of zombie-fueled downloadable content, saying The Sacrifice will be available to Left 4 Dead and Left 4 Dead 2 owners on October 5. As with The Passing, the add-on will be free for PC gamers, while the Xbox 360 version will cost 560 MS points.

The Sacrifice is told from the perspective of the original game's crew, operating as a prequel to The Passing. In it, the survivor contingent makes its way South in the lead-up to meeting up with Left 4 Dead 2's cast and passing on the gameplay torch. The add-on will also introduce the "sacrificial gameplay" mechanic, where players can decide who will die to save the rest of the group.

For more information, check out GameSpot's previous coverage of Left 4 Dead 2.