Tripwire Interactive announces that Killing Floor has sold more than 1 million copies on the PC, celebrating the milestone with a sale on Steam where the action game and all its DLC can be had at an 85% discount. They also offer some sales stats for the game:

• 1.1 MILLION copies of Killing Floor sold on PC in 2 and a half years
• Nearly 2 million Killing Floor DLC packs sold
• 45 MILLION hours of Killing Floor played to date
• 440 MILLION Zeds have been dispatched in Achievements alone - including more than a quarter-million Christmas Santa
• Zeds are being killed by you at the rate of over 20,000 an hour!
• Hundreds of custom maps have been created by the community