It's being wiped and given to an eleven year old gamer. Thanks in advance. The best game on it now, is Punch Quest.
It's a shame as its basically bricked by Apple. Maybe there's some solutions, but essentially you're looking for older games. Another possible is maybe putting custom ware on it, not sure how advanced that is.
If it's iOS 5.1, you can get Bastion, Girls Like Robots and King of Dragon Pass, which are all still excellent - though KoDP might not suit every 11-year-old. Then there Ridiculous Fishing, Muffin Knight and Infinity Blade, which are all bona fide iOS classics, if anything is on iOS. Ooh, found one more: The Bard's Tale. Great music, good action, decent graphics and funny - it's perfect for an 11-year-old. (Also, if you're inclined to the greyer side, there's GBA4iOS...)