Rumour: Overkill working on Left 4 Dead prequel

Payday: The Heist developer Overkill's Left 4 Dead collaboration with Valve is a full game that prequels the last two games, CVG's reporting.

The game will apparently tell how the zombie outbreak first originated in the first place.

The studio, recently bought by Syndicate developer Starbreeze, announced last month it was collaborating "in-depth" with Valve on a L4D project. A Payday sequel is also thought to be in the works.

The original Left 4 Dead came out in 2008 and was followed a year later with Left 4 Dead, both on Xbox 360 and PC.