Sources:
https://github.com/HackerPoet/NonEuclidean
This is a game engine written with C++ and OpenGL for using in games with non-euclidean geometries. The engine has several interesting example rooms, that shown on the video.
It's a cool example of non-usual rendering, that can't be achieved with standard engines like Unity.
The engine may be a good example of OpenGL programming - it's lightweight and easy to build and understand. It uses glew library for access to OpenGL extension. It's really nice to play with demo rooms yourself: