Last December, Valve announced that their zombie co-op shooter Left 4 Dead 2 had sold over 2 million copies in retail stores in the game's first two weeks of release. This week, Electronic Arts, which distributed the game in retail stores, announced during their conference call to investors that the game has sold over 2.9 million copies worldwide for both the PC and Xbox 360 ports.

Naturally both these numbers do not include the number of PC copies of the game that have been sold directly via Valve's Steam client. Valve has kept those numbers completely secret but its likely that if added to the retail sales it would increase the total unit sales to well over 3 million copies.