World of Warcraft developer, Blizzard Entertainment, is celebrating the response its first expansion pack had to the game with the announcement that it has sold 3.5million copies so far bringing the overall global total of subscribers to 8.5 million.

Launched in mid-January in North America, Europe, Australia, New Zealand, Singapore, Thailand, and Malaysia, Blizzard had previously announced that this first expansion set for World of Warcraft sold through nearly 2.4 million copies worldwide in its first 24 hours - more than any other PC game in history had sold within an entire first month of availability.

The success has had a knock on effect with the game's worldwide subscriber base now more than 8.5 million.

World of Warcraft: The Burning Crusade is Blizzard Entertainment’s first expansion for its subscription-based massively multiplayer online role-playing game, World of Warcraft. It added an extensive amount of new content to the game, including an increase in the level cap, complete with new spells, abilities, and talents for players to acquire as they advance their characters.