For Tripwire Interactive, the only way to celebrate is by slashing prices. The studio's co-op survival horror game, Killing Floor, is on sale for $2.99 as a result of recently selling its one millionth copy. Over the last few years, Killing Floor players have racked up 45 million hours of playtime and killed over 500 million enemies. Man, that floor must be getting stickier than a neglected cinema aisle.
You have until Thursday to take advantage of the sale.