nice! how are you thinking of implementing the aiming? i was thinking about pressing the screen and holding to aim and releasing to shoot. or maybe an automated back-and-forth movement?
Well I think the bottom of the screen will be empty, as the game use a square space and the phone has a rectangle screen. So pressing in the area bellow the screen would let you fire in the line from your finger to the ball, like a slingshot You could also press directly inside the game area, but then your finger hide where you are aiming.