A specialized programming language for 3D geometry generation + manipulation called Geoscript as well as a Shadertoy-inspired web app for building stuff with it: https://3d.ameo.design/geotoy

There have been lots of cool technical challenges through the whole process of building this, and a very nice variety of different kinds of work.

I'm working towards using the outputs from this language to build out levels and assets for a browser-based game I've been dabbling with over the past few years.