This was fun! I liked the animations of the enemies and their projectiles.
I struggled a bit with the next level starting immediately, sometimes it made it hard to retrieve my bullet before being ambushed. Sometimes the hitboxes on the final 'pop' of enemy bullets was also a bit unclear - got clipped a couple times after I thought they'd expired.
The upgrades were interesting, the exploding bullet in particular, but enemies usually moved away long before it had a chance to pop, would have loved to have been able to use it a lil' easier. I was offered the same upgrade twice at the same time quite often, rather than two different ones.
I also encountered a funny bug, one of the enemies suddenly started accelerating massively until eventually it disappeared. Unfortunately this did render the level unclearable.
Overall, a great take on the prompt, well done!