First and foremost, the game looks great! The color palette is very well chosen, the bosses' design is superb, the invincibility mechanic with the dash is very cool once you get the hang of it, and that single point of life is of course the whole flavor of the game... in short! a lot of very good things in this game :D
I beat the first two bosses in about 60 deaths. They're difficult but make you really want to improve in order to beat them. Then after my 108th death, not being able to beat the 3rd boss, I stopped. My only gripe is perhaps with the third boss, whose difficulty I find a little inflated by its very high number of hit points. I had the feeling I was doing my best, but the length of the battle was too long, so there was always a small mistake that would prove fatal. But maybe others will find that very challenging. In any case, I'm very proud to have managed to beat him, and maybe I'll try to make him regret all those deaths he inflicted on me!
In any case, congratulations on a game with a superb atmosphere and very engaging gameplay.