DayZ isn’t finished yet, but that’s not stopping thousands of gamers from picking up the survival shooter.

Developer Bohemia Interactive has sold more than 800,000 copies of DayZ since it debuted in December, according to creator Dean Hall (via Destructoid). At $30 per copy, the zombie title has already earned an estimated $24 million.

“We — Bohemia and I — had very ambitious plans for 2014 already, however, this amount of sales was completely unexpected,” Hall wrote in a post on Reddit. “Honestly, 250,000 within a quarter was what I would have considered a success. So to move nearly 800,000 in under a month is crazy.”

DayZ is an open-world online shooter that has players attempting to survive in a zombie apocalypse. They can gather up supplies and team up with others to attempt to overcome starvation, the undead, and other humans.

The survival game is available to purchase now in a test state through Steam’s Early Access program. Those that purchase it now will also get the final-release version of DayZ at no extra cost when Bohemia finishes it.

Hall confirmed that the huge influx of cash will help the company with development.

“We’ll be finalizing our [development] roadmap in mid-January, but it is safe to say that this kind of result will be having a very positive effect on that roadmap,” he wrote.