General Drop - For The iPhone. General Drop is a physics puzzler that will keep you entertained for hours on end. Your mission is simple, using only your trusty rifle you must destroy a variety of targets in order to return your general to his base. Use your device's accelerometer to place the crosshairs on your target and tap the screen to fire your rifle. Each level presents a uniquely challenging barrier between your general and his base. Successfully completing a mission requires not only deadly accurate sharp-shooting, but also the ability to think fast and use creative problem solving. Nobody said this was going to be easy, but I can tell you one thing. Strap up your boots because with 64 levels of non-stop shooting, TNT explosions and a targets of all shapes and sizes--its going to be a bumpy ride. 

There is a calibration button for the accelerometer so that you can set your own custom neutral position for the cross hairs.

Source: http://itunes.apple.com/us/app/general-drop/id432019964?mt=8