Multiverse is a 3D game that I plan on making in C, not C++ because C++ is unstable and excessively complex, and I can implement several features that C++ has into C myself.
For now, Multiverse is only available for linux (and you have to build it from source), but soon it will be available for windows, and mac, and then android and iOS, wwhen development starts catching up pace.
Most of Multivere's code will be written in lua, which can be found in the scripts directory. To launch Multiverse the right way, you must run Multiverse with an argument as the path to the main.lua file which is found in the scripts folder. The command make test already does it for you.