So after playing, I read through a bunch of comments on both this page and the game's itch.io page. I'm very surprised to hear that you're not used to making pixel art, this looks great (especially the synthesize menu)!
I came across a lot of bugs unfortunately and was not able to have any synthesized creatures actually do anything other than move continually against the left wall. Obviously this is a big mechanic to take on with a platform like GB, and in such a short amount of time, it'd be tough to accomplish for anyone I'd imagine. I see that you are considering working on the same concept in a more modern engine, I think that'd be great!