Amazing job! The art is very nice, and I love the music.
The gameplay is very nice and super easily understandable.
The choice between an upgrade or a ship repair is very clever, where you choose between finishing quicker but more difficulty, or slower with a bit of an easier time
Suggestions:
- Prevent monsters from spawning too close
- Maybe zoom out the camera a bit to see them come from farther?
- You could add a bit of camera movement based on the mouse direction to add a bit of juice :D
Very solid game!