wow1Today, game maker Blizzard Entertainment (a division of Activision Blizzard) kicked off its Blizzcon conference and announced that it will launch a new expansion pack for World of Warcraft. The game, World of Warcraft: Cataclysm, will debut in 2010. There are 20,000 Blizzard fans at Blizzcon in Anaheim, Calif., who are no doubt going wild over this.

World of Warcraft is a billion-dollar franchise, first launched in 2004. It has 11.5 million paying subscribers (though the fans in China have been without the game since June). The company has only launched two expansions — or add-on software that you pay extra for in the store — in the past. The last one, World of Warcraft: The Wrath of the Lich King, sold 2.8 million copies in its first 24 hours last November. That made it the best single-day seller in PC game history. The Burning Crusade, released in 2007, sold 2.4 million copies in a single day. With Cataclysm, you will be able to increase your character’s level to 85 and play characters from a brand new werewolf race.

Blizzard also has another game, Starcarft II, coming in the first half of 2010. The company launched the original Starcraft a decade ago and it seemed like it was ready to launch this year. But delays in revamping the online service pushed the game to next year. Another game, Diablo III, is also coming sometime soon. When these games arrive, they’re going to occupy hardcore gamers for a long time.

If it isn’t obvious by now, rival game publishers are going to have to pay close attention to the release dates of these games and run as far as possible in the other direction. Here’s a video on the new details that Blizzard disclosed today at Blizzcon about Cataclysm.