Tripwire Interactive announced that Killing Floor has crossed a million sales.

In addition, almost 2 million downloadable content packs have been sold, and players have clocked 45 million hours in the game. Players have taken down 440 million zeds, including roughly 250K Christmas Santas. The zed massacre is still ongoing, being killed at a rate of roughly 20,000 per hour.

"As a truly independent outfit who have funded ourselves all the way, we are particularly proud of the achievement," the company wrote in a statement. "Our thanks go to all the developers of the Killing Floor mod and everyone on the team here at Tripwire Interactive, who's continued support has made the game such a huge success. We would also like to thank all the members of the community who have made maps and other add-ons for the game, with the Killing Floor SDK. And, most importantly, we offer our thanks to all of the fans and everyone who has bought the game over the past two years and helped make Killing Floor the cultural phenomenon that it is today."

The Killing Floor released in 2009, but has seen consistent support with new updates and promotions, including Summer Sideshow and Twisted Christmas events this past year.

To celebrate, and no doubt to sell even more copies, Tripwire is offering the game for a whopping 85% off through Steam as the digital retailer's "Midweek Madness" sale. That brings it down to $2.99 through February 16. The Killing Floor bundle, which includes various character packs, is down to $4.78 through the same period.