This was a cute little metroidvania and I'm very impressed how you managed to put so much map in the little game boy screen.
The game itself is obviously not that complex, but the context of the limitations you had make it a whole lot more impressive.
I have a few nitpicks still.
The boss fight was so unpredictable that I didn't even try to fight it and just cheesed it by shooting through the wall.
And also sometimes my jump input was eaten. No idea why though.
Really cool entry. Keep it up.