Lovely puzzle game. I've had fun playing with cellular automata, and thought about how it would be neat to have a puzzle game with them, but never could quite arrive at satisfying mechanics.
This is a perfect example of what I would've wanted to make with this concept, if I'd thought of it. The visuals and audio complement it well. My only minor complaints are the lack of an on-screen back button, and the lack of an indication that the rule list could be scrolled. For both of those, I had to scroll down to figure out how to do it/if I could do it.
It's easy to see why they were omitted, though, as you already were coming hitting the 64x64 limit. Great work!