Nice game! I really liked exploring the world and figuring out the solutions to the different puzzles. It definitely has the vibe expected of a GameBoy game! I got three puzzle pieces and kept trying to look for the rest before deciding to check the description to find out the rest of the pieces weren’t implemented.
I played this on stream today (recording here), in case you’re interested in watching a playthrough. I did find some missing collision tiles and wasn’t sure if that was meant to be part of a puzzle, but it seems not.
Good job and hoping to see this expanded in the future!