Nice little shmup! I think the controls would be better if either the shooting direction is inverted from what it is now, or if the ship didn't move while you held down the shoot button. Also think it would be more satisfying if your bullet moved in a bigger arc and killed multiple enemies. Great work!
I will definitely add an option to toggle if the shot direction is inverted.
Not moving is dangerous, especially since charging takes longer the higher the difficulty.
You can upgrade your "Skill" in the Shop for it to move farther and wider arcs and your "Power" to make it bigger and stronger.