Unfortunately I can't play this right now :p
But I still feel like rating this, so I'm basing this on the video and comments :/
So, I gotta say, this looks amazing! The artstyle is nice. Definitely looks like a game that could have released on the the gameboy.
The only thing that I noticed (immediately) was the music. It's definitely not bad, it's very good in itself. It's just that, it feel more like a SNES track than a GB one, and Ik the GB can play (very low quality 4bit) samples, but im 100% sure they can't be THAT high quality.
Still though, from what I can see, there was definitely a lot of time and effort put into this one! :)