A really fun game I found is called 3D Lawn Darts. It uses the camera on the touch to allow a realistic throwing simulation of the darts. You literally swing your arm with phone in hand as if you were throwing a real lawn dart. There is a free trial version of the game online. You can play about 3 or 4 rounds against an opponent or the computer for free on the trial "backyard" scene. It's not story based as the OP asked for, but this is a very fun game.
Link:
http://www.concretesoftware.com/prod...awndarts.shtml
Another game I love, also not story based, is called Pocket Sand. This is also an addicting game, although I over played it. There's absolutely no purpose to it. If you're interested in trying it check it out here:
http://handheld.softpedia.com/get/Ga...nd-25068.shtml