Your feedback form doesn't allow people without permission to view, so Ima write my thoughts here!
I love the simple pallet design and RNG (probably) parts of the world design!
I also like how there are powerups like the blue speed that spawn at the end of some levels, though I'm not sure if they're permanent - which I believe they should be.
Some suggestions (not sure if there was a deadline) are to add
- A menu and loop of the game instead of exiting the game on death.
- BGM and SFX for obvious reasons.
- Perhaps a screen shake when you shoot OR when you land a bullet to add some polish.
- Multiple enemies (not sure if there were further down the line), but obviously a slow, tanky, damaging one, as well as a fast, squishy, weak one for basics - for some spice.
- As well as maybe more powerups (Again, didn't get to far but perhaps maybe the heals can also add a buff like more ammo or damage up).