You could also consider Diablo 3 on account of its auction house (once it actually starts working). It's very fascinating to game the market and turn a profit,

You could also consider Diablo 3 on account of its auction house (once it actually starts working). It's very fascinating to game the market and turn a profit, and I'm sure there's a lot of things outside of videogames to be learnt from using it. As of now, the auction house is basically the unofficial endgame of Diablo 3.