Although it's now 4 years old, Blizzard's World of Warcraft retains its number 1 position as the most popular MMO (massive multiplayer online) game.

First released in 2004 in the U.S. and 2005 in Europe the game now has over 11 million loyal followers around the globe. The latest extension, Wrath of the Lich King, immediately attracted thousands of eager players when it was simultaneously released in North America, Europe, Chile, Argentina and Russia. The previous popular game extension, The Burning Crusade, sold around 2.4 million copies in the first day of its release. This record was broken by the latest release which sold 2.8 million copies in the first 24 hours.

Being a WoW fanatic is not a cheap hobby. In order to play Lich King gamers will have had spend cash on the upgrade from the original WoW, plus more cash for Burning Crusade and then pay the monthly subscription of £8.99 before shelling out another £24.99 for this latest extension.

So what is the secret to World of Warcraft's success? There has certainly been no shortage of challengers for the lucrative number one position as the most popular MMO game. Funcom's Age of Conan and Electronic Arts' Warhammer Online use similar, fantasy, fictional environments but don't yet have the established player-base enjoyed by WoW. If they develop their user base perhaps they will lead in 2009.

But we haven't answered the question regarding why WoW is so popular. If you are aged around 12 or 13 and all your friends are playing WoW online which game will you be asking for this Christmas? This is a crucial reason why the game is successful.

Another key factor is how Blizzard have made the game accessible and engaging by making it simpler than older MMO games. This has made the game less off-putting and more engaging to many new players. This is another significant reason why WoW is the success that it is. And another outstanding feature is, of course, the graphics. The characters and game environment are very engaging and well designed.

What is particularly striking is that, although the world is diving into an ever deepening economic recession, there is still enough spare cash around to spend on escapist entertainment like WoW.