Fun game. I really enjoyed the charge up mechanic, it felt satisfying to charge the boomerang up to a higher level and the sound and effects that accompanied it. The lasers during the boss fight and chromatic aberration was really cool too :D
I definitely could not beat that boss after a few tries, but I can see a way through if I was faster. Maybe some HP pickups would help! I see you mentioned the issue with the cursor, that might have made it a bit difficult for me to aim as well!