Fantastic job, you nailed the gameboy feel thats for sure. As others have said, a little more onboarding could go a long way, but since you were going all in on the gameboy era, you even nailed that (i remember having to flip through a lot of manuals back in the day lol).
Think others have mentioned it as well, but the game screams gamepad and I hooked mine up and was super excited.. then was super sad haha.