A lot of things here that feel like a gameboy game, like the slight delay on the swing on the bat of all things actually reminds me of a specific gameboy game (a Star Wars licensed game) that I have the actual gameboy cart of, the visual style evokes the feel of gameboy quite well for the most part, the song that plays feels mostly gameboy enough, though I do have one slight gripe on that front: The particle effects feel a bit more than what gameboy could've done. Still, very small gripe on that front, overall it's evoking that feel well.
Gameplay is quite good feeling here, I can't think of another game off the top of my head with a jump as low as you start with in this game where the jump still actually felt good to use. (Of course, this being a Metroidvania, it gets higher over time. Still feels good.)
Also, the ending got a good chuckle out of me.
Great entry you have here.
btw: Encountered a weird visual bug where if you press a button during the opening cutscene, the title screen text flashes again. Nothing huge, but worth a mention.