Interesting concept! I have a couple of critiques:
- Allow for WASD movement, since that is standard for shooter games
- The camera shake was a little disorienting, but I liked that it was there!
- Movement was a little slidey, perhaps tighten it up a bit
- The game was too hard straight away, consider adding some very easy levels to start next time so that players have time to acclimate to the controls and gameplay
- Shooting sound effects would have added a lot to the game
I think with a little extra work this game could be great. I hope the feedback helps!