The news comes as anticipation builds for the release of the game's second expansion pack, , which launches on November 13.

"Since debuting in North America in 2004, World of Warcraft has become the most popular MMORPG in the world," Blizzard announced in a statement today. "In addition to being the bestselling PC game of 2007, expansion holds the record for fastest-selling PC game of all time, with nearly 2.4 million copies sold in its first 24 hours of availability."

World of Warcraft is unique (compared to most games) in that gamers must pay a monthly subscription fee of US$13-15 per month to play, in addition to buying the game for $30. The MMO has also drawn criticism from disgruntled spouses and researchers for being abnormally addictive.

GamePro awarded four and a half stars to in 2004, and five stars to last year.