The collaboration between Valve and Payday: The Heist makers Overkill that was announced last month could turn out to be a Left 4 Dead prequel, or so goes the latest rumor from E3, at least.

"We are excited to be able to confirm that an in-depth collaboration between OVERKILL and Valve is currently in production," said Overkill director Ulf Andersson in May.

At the time he didn't reveal any details, but several sources are reporting that the project will in fact be set in the Left 4 Dead universe and take place before the events of the current games in the cooperative zombie apocalypse series.

"We are working on a very cool blend of Payday and Left 4 Dead," Andersson said upon the initial announcement. "I am sure it is so exciting that it will have some players check into the hospital before we are done."

We'll be slightly disappointed if it's not Zombies & Robbers (like we originally predicted), but we're not ones to complain about more Left 4 Dead. Will you? Or would you rather Overkill concentrated on the Payday sequel? Tell us in the comments or on Twitter.

[via CVG]