For those who want an actual first-person shooter gaming experience on their smartphones, the iPhone Appgun might just do the trick.
Designed by Apptoyz, the iPhone Appgun uses the camera on the phone to display surroundings which will then pop out a few aliens for you to kill. Simply download the game (it's free), insert the iPhone and it's good to go. While you may look crazy for shooting at nothing, it's still an interesting accessory. The iPhone Appgun costs around $30 and will hit stores in April.