Just a month after release, Call of Duty: Black Ops has already become the USA’s 7th best selling game ever released. According to recently released NPD sales data, the game has sold 8.4 million copies on PS3, Xbox 360, Wii, PC, and DS combined so far.

Its predecessor, Call of Duty: Modern Warfare 2, sold 6 million units in its first month. According to NPD, Black Ops accounted for 25% of all physcial unit game software sales in November 2010.

Curiously, CoD: Black Ops was not as well received by critics as its sales figures would suggest. The PC version is essentially broken, and there has been no shortage of issues plaguing the PS3 and Xbox 360 versions.

In fact, Black Ops came in as the 28th most highly rated game by reviewers in 2010, according to Gamerankings, which indicates that hype soundly trumps critical reviews when it comes to influencing purchasing decisions.