Save points add to the challange of the game, however, the main problem with checlpoints is that they don't allow you to quit whenever you want.
Games with checkpoints need to implement a system that allows you to quit the game whenever you want and than return to that exact spot when you come back to the game, that way the challange remains and you can stop playing whenever you want.
Bet with Dr.A.Peter.Nintendo that Super Mario Galaxy 2 won't sell 15 million copies up to six months after it's release, the winner will get Avatar control for a week and signature control for a month.







