LOS ANGELES--In Valve's 2008 zombie shooter Left 4 Dead, players faced an onslaught of undead, but how did these nasty creatures get there in the first place? According to a new report at CVG, a Left 4 Dead prequel is in development at Payday: The Heist studio Overkill Software, and will explain that very question. A Left 4 Dead prequel would explain how this scene came to be.

　　No further information is available on the project, and as of press time, neither Valve nor Overkill Software had responded to GameSpot's requests for comment.

　　Late last month, Overkill Software announced a partnership with Valve for Left 4 Dead, though it was not explicitly clear what the two companies were working on together. At the time, Overkill described the project as an "in-depth" collaboration and a "very cool blend of Payday and Left 4 Dead."

　　The latest entry in the Left 4 Dead franchise was 2009's Left 4 Dead 2, which was developed by Valve and published by Electronic Arts. If Overkill is in fact working on a Left 4 Dead prequel, it won't be the only project the Swedish studio is building. A Payday: The Heist sequel is also in development.