My guess is that in a good fighting game all the characters need to be reasonably different to each other but also well balanced against all the others. The ba

My guess is that in a good fighting game all the characters need to be reasonably different to each other but also well balanced against all the others. The balance will require a lot of play testing and tuning, so each character you add will more expensive than the last. And there's also the more mundane possibility that a fair chunk on the money is submission costs for Xbox Live Arcade and PlayStation Network.