This is a great little game, I enjoyed playing through it. I love the art and music and the fact that it can be played on a GameBoy is awesome.
I found the hit detection on the player a little wonky. With the bosses specifically, it was a bit hard to tell if I was hitting the boss or if I was getting hit. I also found a bug with the final boss where it and the one minion left didn't do anything after I died, respawned, and came back. I was able to just walk and hit it until it died.
Fantastic effort and a great game.