Well done in that short time! But as others said, it is quite the task to finish it, but I finished the last level with 4 spitters too.

I think you decided on the right scope for the time and executed it nicely! Everything is self-made, which is amazing. It was a bit to precise but for the game jam perfectly fine! 

It is a little hard, I need more box buoyancy. But nice mechanic!

I like the art and the sound, it has a little retro vibe.

The levels seem a little bit hard, because you have to play almost perfectly. I would give an extra time freeze to every level to let space for some errors.

When there are shooting enemies, they can reach you at the start, I would give them range, because it's frustrating to die if I don't start moving instantly.

These are mostly level design issues, the game mechanic is interesting.

I am bad at platformers, and this game is very hard. But the idea is great! Good job.