I enjoyed this, it was simple but had enough challenge with the different shells and various obstacles. The last level with multiple planes was a bit too tricky for me though, maybe if the bombs they drop were slower or you had another way of stopping them.. it could also be that I'm just bad? ahah
The art style is very nice, I like the glow of the shells and the general look and feel of the game. The use of Moonlight Sonata, while not particularly original, was also very soothing.
My only real complaint is a lack of sound effects, which I think would've added a lot. Oh and maybe shortcuts to launch the different types of shells instead of clicking on them, personally this would help me a lot to focus more on dodging.
Great job!