Woah, what an incredible game! This really has the capability of being a finished game in my opinion.
From the controls, the mechanics, atmosphere and the bossfights themselves, everything seems incredibly well thought-out and polished!
The art is incredible, and the sound design is great!
At first, I thought of saying that the reloading mechanic could become a bit annoying. But I feel like it's implemented in such a satisftying way, that it eliminates all issues I had with it (also after a while you get used to it and it's satisfying to hear the sound and animation).
The "regenerating life" mechanic is implemented in a very original way!
Maybe my biggest issue was with some bosses having a bit too much projectiles spammed at the player, but not too excessive.
Nothing else to say! Fantastic game!