[pcouy]

Another commenter shared https://github.com/GollyGang/ready which may be what you have in mind. I clearly see the fun in building such a thing from scratch though, and I intend to make a simple web-based one. Let me know if you create a repo for you project, I'll make sure to take a look and try to contribute if I'm comfortable with the tech stack.

Edit : Ahah I just noticed the "other commenter" is you

[danwills]

Heheh indeed it was! - What I was saying above though is not just for exploring RDs but more for actually building things out of them!!

It's a rather out-there (non-serious) idea where all the usual 'stuff' of a GUI is actually made out of dynamically-simulated-CA/RD cells interacting with each other.

Let's say for example once one had developed some way to reliably simulate a dynamic but smooth and stable enclosed area with a boundary (like a bag?), well you could call that layer a 'window'-ish-type-thing and constrain the sub-simulations (ie the window-widgets) to only grow inside the window. Window-docking could perhaps have behavior a bit like bubbles-adhering-to-each-other as a natural outcome of the simulated-nature of them and wobbly-windows could be made to be a natural outcome of there being the wave-equation as one of the formulae being used, and other things like that.

It's definitely an out-there idea not really intended for regular-consumption but I think it could be super fun to explore especially for playful in-game-UI use-cases.