Touchscreens work fantastic for certain types of games, but when there's a lot of fast action, a physical joystick is the only way to go. And researchers at Keiko University have developed a controller that doesn't need batteries or a connection to your device.
Unlike the JOYSTICK-IT which provides similar functionality by physically pressing on the touchscreen, this joystick sits over a phone or tablet's front-facing camera. It's made of a soft rubbery material so as you push it in all directions it deforms, and on the underside is a set of markers that are tracked by the camera as they skew and move. Translating the physical motions into the game.