The game feels a little short (only about 3 or 4 ennemy waves) and there's no way to see how long you're playing (a score system would have been great). Maybe also making sure the ship moves with the same increments of space, otherwise the shooting can get tricky sometimes.
Besides that, I do feel like you tried your best on the game, you didn't make any music sadly but you made some SFX, and if you didn't had any musician I can understand it. I also like how the player's bullets are slightly different from the ennemies ones.
It was a short yet fun experience, good work!