The game feels great to play, jump and shoot around. Especially the deflection mechanic
It's very difficult though.
The thing I have most problems with is the boss. While conceptually it's great, the fight feels very random. As far as I noticed the time the boss takes after shooting at the player and before the next shot is random. And this sometimes makes the fight very drawn out, if you get bad rng, but the number of enemies keeps growing no matter what. It would also be nice If the boss shooting the bullet was more telegraphed than just through an animation, prehaps a sound effect or some additional light effect?
One last thing was that when I finally beat the boss, the enemies kept spawning. I thought the game was broken, but decided to keep playing. Only after a few minutes, after I was starting to consider that there is no win screen or that my game is broken, they stopped spawning an the door opened. I think that was way too long of a wait after beating the boss.
But even with the problems I had, this was still a blast to play. Very well done!