10 million is crazy talk. CoD4 is exactly the type of PC game that gets pirated, not bought.
Activision or rather Infinity Ward said that PC sales were rufly a 10th of how much CoD4 sold on consoles (although this was just a couple of months after release, and I agree that PC has longer legs).
I'd guess Activision meant 7 million copies shipped in 2007. Probably a bad worded press release that made shio believe they meant 7 million sold at retail to customers.
My estimation is that CoD 4 sold 2-2.5 million on PC, but many of those copies have probably been sold cheap on Steam at $15 or $20 a piece.







