How MMORPG's suck people in so much with its addictiveness is very easy. Just spread the content very thinly but not too thin so it looks acceptable to level up so you can claim your prize you will get on level X. It creates addictive gameplay but is it fun? No, MMORPG's have very boring core gameplay but seems "fun" because of the huge chatbox thing and offcourse the leveling up thing with rewards on specific levels.

Say a bit of this game at the London Anime Expo back in October 2005. It looks damn good too with some nice character designs. I hope Codemasters do it justice.