Yo! I had almost this exact idea for a game years ago, and you actually made it! Great job!
If I do ever make the game that I have in mind, I'll be sure to let you know!
Cool! I'm gonna try it out! Were you inspired by BoBoGram in the making of this puzzle?
Also, I'm reading that BoBoGram was inspired by Abdec: https://letibus.itch.io/abdec, another pencil and paper "discover the rules" puzzle!
Great game, but I couldn't finish it because one of the later levels (one with Preta, Bird, and Snake), I couldn't get Snake to appear, no matter how many times I restarted.
I was wondering if you might consider making a level maker for this game? There might be a way to encode / decode level files so that people can download and import them from each other by sharing w/o the need to store them on a server. Just an idea.