State of Decay Becomes Fastest Selling XBLA Game Whilst Dev Waits on Microsoft Go-ahead for MMO Sequel

State of Decay, the open world zombie game from Undead Labs has become Xbox Live Arcade’s fastest selling original game ever.

Announced via Xbox Wire, the game has surpassed 500,000 downloads since it released on June 5. A massive achievement for the team and Microsoft Studios.

Undead Labs are eager to get to work on a zombie MMO codenamed Class4, however they are waiting on confirmation from Microsoft, as explained to Eurogamer:

“We cannot begin working on Class4 without a greenlight from Microsoft (who owns the IP, as part of the bargain that led to the funding and development of State of Decay) and a mutually agreeable contract. We have to agree on where we think the technology is going to be in a few years (since the game will take a few years to develop); we have to agree that we have the same goals; and we have to agree on how we’ll collectively run and support the final game.”

State of Decay is headed to Steam some time in the future, with Undead Labs also working on a sandbox mode which is set to bring “pure survival simulation” to the game.

You can pick it up on Xbox 360’s marketplace right now for 1600 points.