no playing until after homework, and not more than 1 hour a day - extra time can be earned by doing extra chores - thats our rule.
my son has already lost about 3 games, i keep telling him "put them in the case when you take one out, one needs to go back in" but at 7, he just hasnt quite got it yet lol.
my son loves the super mario bros, pokemon games, cooking mama, sonic rush and bowsers inside story. I loved scribblenauts it was really fantastic, also trauma under the knife, the professor leighton games, i also secretly loved super mario lol.
some games not worth it are zoo tycoon for ds - so much better on the pc and lionel trains was really hard to work out.