Before CoD 4, the series was rather obscure compared to the big games of the early 2000s. The sales figures aren't too great, and clearly there wasn't too much talk of the series because I and none of my friends had even heard of Call of Duty until Modern Warfare. Suddenly, MW comes out and is the coolest thing ever, breaking all sorts of ridiculous records and whatnot, being a serious and almost fatal competitor to Halo 3. How did CoD's popularity suddenly explode? To me, the series seems to have come out of nowhere.