Undead Labs has announced another milestone for its zombie apocalypse simulator, State of Decay. The developer is celebrating 2 million copies sold across Xbox Live and Steam.

The company doesn’t have any new announcements, but it promises a month of festivities to commemorate the good news. The title was first released on June 5, 2013, on Xbox Live, reaching 1 million copies sold in October.

Since then, the game released on Steam in November 2013 and two expansions (Breakdown and Lifeline). An Xbox One version is slated for release in Spring 2015.

[Source: Undead Labs]