the game has some good nes looking sprites, plus the boss's music was really good lol, even tho the music in general is a lil bit too short and repetitive :') , it took me some time to realise that i can only hit the when he's doing the "coughing animation" (i think cuz he prob swallowed his tongue XD), also the enemies can sometimes wipe you out a bit too quickly, so i'd say maybe make the i frames just a bit longer, and also the boss attacks a bit too fast after he recovers but that isn't a big problem since i adapted to that, but other than that the game is a lil short but it's fun nevertheless
also if you have some free time maybe you can check out my game and give it a try? i'd love hear your feedback :)