Good game. I had a lot of fun playing it.
I was surprised when tougher enemies get out of the pit, I would appreciate some visual info about that - size or something.
Also, some pause between levels would be great because I caught a cramp in my hand from the controls and I didn't have time to stretch it out.
Boss was kind of easy. It would be better if the boss would targets cannons primarily because I didn't have to move at all during the boss fight. And if you find a good distance between cannons you can just move around the pit without changing direction and just keep shooting. No enemy can pass this.
Anyway, what is most important, I had fun playing your game. Great work. Thank you.