The game is nice and i like all the atmosphere. It is really difficult (at least for me) and It make me crazy to start over also after on hit.. maybe you could give him 2 or 3 lives .
I will definitely be making it more than 1-hit for a future version. I think after having to fight these bosses like 100 times to test for bugs I didn’t notice how difficult it ended up becoming so its really helpful to have your feedback!