Due to hit PC and Xbox 360 in "late March," Kotaku reveals, The Passing will see Bill, Zoey, Francis and Louis crossing paths with L4D's survivors and encountering a new 'uncommon common' infected named the Fallen Survivor who sometimes drops items.

Further content will also come for the original Left 4 Dead in the form of an add-on telling of the fab four's journey to The Passing, a "month or so" after The Passing hits.

A digital Left 4 Dead comic book illustrated by Powers' Michael Avon Oeming and likely starring the original cast will also follow in the wake of The Passing.