I just found Ghostbusters Paranormal Blast in the iTunes Apps store. This is a game where you need the camera, and gyroscope on your iPhone or iPad to play. I actually first got to play this game at PAX East a couple years ago. At the time they couldn't give me an actual US release date.
In order to play the game you need a back sided camera on your phone and the gyroscope, as I said above. The reason for this is that the game is designed to use your location as a place to bust ghosts. It uses your location services to try to find any areas such as libraries, and other public places you can go to, to bust ghosts. Unfortunately due to where I live, I am unable to get that part to show up correctly, but it still lets you go ghostbusting at your current location anyway, you just need to tap on any location shown on the map in the game.
When you go to bust ghosts it's a pretty cool concept they have. it uses the camera to help give you a first person perspective of being a Ghostbuster. I have to say it's my favorite IOS game to date. It's a lot of fun, and I can't put it down. The only draw back might be that it's too short, but with that being said you also can't expect an IOS game to be long either. Over all I have to give Ghostbusters Paranormal Blast a 5 out of 5. The game is too fun to not play!