World of Warcraft.

I havent played it, but from what I've read, its way too linear and level-locked.

For the caliber of minds that generally play p*ker well (you especially, Exit, with all the aptitude you have for math), I think Anarchy Online is a much better game. Much more in depth and actually requires thought.

That being said, the economy is totally [censored] right now. Its still the best MMORPG I've ever played. And you can get a feel for it for free, for as long as you want to.