That was fun. As people said, enemies must have a bigger variety of attacks. They must force you to do something else besides just spinning . Maybe even the boundaries of the screen could hurt you in order to force the player to go to the center.
I love the sound effects and music. The ship's color is way too similar to the background color. I know it creates harmony, but I'd like it if they weren't merging together this much.
I'd like to see a boss battle next!