Concerning on this question 'World of Warcraft' production director J. Allen Brack answered:
If there was an easy answer, there'd be a lot more successful massively multiplayer online games. We have a very clean interface -- we try and keep everything very simple. We continue to spend a lot of time on it, and we throw a lot of work away. We like to say that the game is easy to learn, difficult to master. There are also lots of rewards: There's always one more dungeon, one more gear upgrade, one more level.It was also a case of good timing. "EverQuest" had been out for many years.

We like to say that players fall into five buckets. We try to satisfy each player. The leveling-up player quests, enjoys the game and levels up. Everyone is in this bucket at one time or another. There's the five-person dungeon player. There's the 10-person dungeon bucket, which has a huge jump in gear and loot. There's the 25-person raid player. And then there is player versus player, with battlegrounds and arenas. Even within the groups, there are more stratifications.He aslo added .