Is this related to or just inspired by LÖVE, the 2D game framework for Lua? https://love2d.org/
From a brief look at the github, though, it looks like a custom 3D engine with VR capabilities. Still, it's not like Love2D's API is particularly complex to imitate. That's one of its major appeals.
I was writing one of these in C++ a little while ago, and I remember being impressed at how easy it was to integrate OpenVR with my random OpenGL application. I got to a simple 'stand behind a barrier and shoot box-zombies with the controllers acting as raycast pistols before I dropped the project...
Anyways, cool stuff! I love seeing more open-source work in low-level graphics, even with existing solutions. I was frustrated by the lack of resources to learn 3D graphics math/APIs, and stuff like this can only help.