Being able to play gun games on mobile devices like the iPad and the iPhone are hardly as fun as the real thing, unless you use live ammo and I'm sure the warranty doesn't cover that. One app, however, aims (no pun intended) to change all that.
The iGunCon for the iPhone
turns your mobile phone into a light gun so you can play shoot 'em up games on your iPad, iMac or MacBook with an actual device you can aim at your enemies.
The app comes with two versions: a "toy mode" that recreates the sounds of a handgun, machine gun and shotgun for those times you want to pretend to be in a gun battle with your easily amused friends and a "controller mode" that works with "Time Crisis 2nd Strike". The controller mode version will only work on the iPhone 4 and iPad 2 since both are equipped with a gyroscope and digital compass.Source: iGunCon