Valve is showing the first downloadable content pack for Left 4 Dead 2, "The Passing", at today's X10 event. The new campaign is now aiming for a March release, the start of new content for the zombie apocalypse shooter.
In "The Passing", players will meet up with the original Left 4 Dead's survivors, Francis, Bill, Zoey and Louis, who will appear as non-playable characters. Valve's Chet Faliszek told Kotaku that Left 4 Dead 2's survivors will rendezvous with the original quartet later on in the campaign, and that they will aid Coach, Nick, Ellis and Rochelle in finishing the third map in the campaign.
That new add-on will offer an opportunity to see more of the original cast's character traits, Faliszek said, storylines that will likely be explored in the Left 4 Dead comic book that will arrive after "The Passing". That comic will be illustrated by Powers artist Michael Avon Oeming.
Then, about a "month or so" after that, Valve plans to release an add-on for the first Left 4 Dead, an episode that will tell the story of the original survivors' journey to "The Passing". That unnamed Left 4 Dead add-on will only be playable on the original game, not in the sequel.
Valve says it plans to release "The Passing" on Xbox 360 and PC in "late March" with more details on the Left 4 Dead downloadable content coming soon.