I really liked this game. The artstyle was simple but I loved how the spikes looked(they changed with the camera). I am proud of winning this game but I would like even more levels. Although 12 levels are more than enough for a gamejam this size.
Things you could improve:
Not sticking to the walls(or keep it if it was intended)
More levels(especially levels like the one with rings, that one was awesome)
Levelcounter and a system so the levels are saved when you exit the game and start it up again.
Some screen at the end when you win with score. If you do this I am going to try to beat your high score.
Sometimes I touched a spike and flew away, that should be fixed.
Maybe have a harder mode where you have limited ammo.