|The shape languages are called "Shape Grammars"|
The fancy geometry is called "Kisrhombille Tessellation"
You make languages out of shapes and then the shapes interact to create complex shapes, the whole process guided by code.
They're fractals. Infinite. And as customizable as code. It's a geometry programming technology.
Here's an overview of the geometry.
Here's a tool for making your own custom grammars (it's easy) and looking at pretty pictures.
There's a README there. It provides a little overview and explains the UI.
There's also a video walkthrough that shows you how to make a simple grammar.
Here's the main project. Much pictures and videos. Fractal dive videos too.
Peruse the github repo for various demos and stuff.