In Backfire you have two guns, one on the top of the screen and one on the bottom. To control the gun on the top of the screen, press up, to switch to the other gun, press down. Once you are controlling a gun, you can move horizontally and shoot. If you have a clear shot all the way across the screen, you can accidentally blow up your own gun. Also if you shoot one of the barriers, your shot is reflected back at you and you have to get out of the way (hence the name Backfire).