This is a good idea, but the shot should not be so continuous and the projectiles should be a little more spaced between them.
The initial position of the shot, and on the left edge of the image, should be in the center. The 'game over' screen too. One touch to start over would be nice. The score display letters (hexadecimal)? The levels, if we stay at the top of the screen continue to increase but not incrementally by 1 (but binary). When you die, it's marked the right number. The image of the character has a point on the edge towards the top right. And lacks audio.