Business is booming in the zombie industry.

DayZ developer Bohemia Interactive sold more than 172,500 copies of the zombie-survival shooter on Steam’s Early Access portal, according to Bohemia boss Maruk Spanel (via Eurogamer). That means the game has already racked up more than $5.1 million in sales.

The title, which has players trying to live moment to moment in a world overrun by the undead, is available to purchase now for $30. DayZ is still in what Bohemia is calling an early “alpha” stage, but the studio is selling it early as part of the Steam Early Access program. This enables gamers to purchase unfinished games and play as developers update them.

Spanel noted that the team has already discovered a number of bugs, and that the company has a lot of “hard work” in its future. DayZ creator Dean Hall confirmed on Twitter today that Bohemia will release a new patch for the game in the next 12 hours.

While DayZ is finding a massive audience, that success has caused the game to go through some early growing pains. Earlier today, gamers were reporting that DayZ was unavailable due to connection errors. Fans looking for answers even overloaded Bohemia’s forums.

About an hour ago, Hall announced on Twitter that the game was back up and running.

DayZ started as a mod for Bohemia’s online military shooter Arma II. The studio then decided to start working with Hall on a full, standalone release after seeing player response to the fan-made add-on.

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