Blizzard Entertainment, creator of the popular MMORPG World of Warcraft, has unveiled plans to create a second expansion for the online RPG that has over 9 million paid subscribers.  The first WoW expansion, Burning Crusade, sold over 2.4 million copies during its first 24 hours of release and more than 3.5 million units in its first week on the market.  The newly announced expansion, Wrath of the Lich King, will add a Death Knight Hero Class, new levels, siege engines, new kinds of character customization, and the harsh new continent of Northrend with its new zones, dungeons and the undead legions of the Lich King.

Blizzard has not yet announced the release date of the new expansion, which the company unveiled over the weekend at BlizzCon in Anaheim.  World of Warcraft is so big that the release of a major new product does affect the entire adventure gaming market (see 'World of Warcraft: The Worst of Times'), but while there is no denying that WoW has taken customers from game and comic stores, there are also a number of tie-in products that retailers can sell including the World of Warcraft TCG from Upper Deck (which had a major presence at BlizzCon), the WoW board game  from Fantasy Flight, the RPG from White Wolf, WoW manga from Tokyopop, plus WoW figures as well as a recently announced comic book series from DC (see 'More Than 9 Million WoW Subscribers').