Undead Labs, the developer behind Xbox Live Arcade sensation State of Decay, has signed a multi-year, multi-title agreement with Microsoft Game Studios.

“We’ll be able to share details later this year, but as with State of Decay, we think it’s best if we just keep our heads down and build some prototypes before we talk too much,” said Undead Labs founder Jeff Strain.

“If this were a press release, we’d have a carefully vetted quote from Phil Spencer, head of Microsoft Studios [pictured], expressing Microsoft’s excitement as well.”

An open world zombie sandbox title, State of Decay sold over half a million copies in two weeks, with half those sales occurring within its first two days on the market. That makes it the fastest-selling XBLA original game in the platform's history.

The open world survival horror title was initially refused classification in Australia, however a resubmitted version with ’supplements’ in the place of ‘stimulants’ was subsequently given an R18 rating.