It is no great surprise that World of Warcraft is as big a hit as it has clearly become. Its 10 million subscribers (no doubt increasing by the second) have been captivated by its ability to be simple to learn, but complex to master. In recent times, it has even managed to keep the more casual gamer playing with its daily quests scheme and an easier levelling curve, a feat that is no mean task when you look at how other MMOs have struggled to maintain their user base. Throw in some excellent marketing (who hasn't seen Mr T or William Shatner advertise this? It even made my mother pay attention) and you're onto a winner. But to keep that trend up, Blizzard needs to keep adding innovation to its Warcraft world and it certainly looks like it's doing that with Wrath of the Lich King.