this is a neat little bullet hell type game. Music and sfx would make it feel a lot better as you said! I also noticed that the controls felt a little weird, especially when you were moving while you powered up with a screw. Adding some sort of visual effect when an enemy is hit would have been nice too as some times I couldn't tell if I was actually damaging them.
All in all though this is a really great first game jam game! Congratulations!