One Of Them was originally developed for the dim3 engine, however dim3 hasn't been updated in years and is fast becoming incompatible with modern operating systems. A stable proof-of-concept of One Of Them has been built for dim3 using OpenGL and compiled for i386.
Meanwhile work is underway to rebuild One Of Them in Unity. The original version was built using chains instead of frames, so the codebase is being completely rewritten.
The full Dim3 demo is available for macOS 10.14 or earlier, and a physics playground demo of the Unity build is available for macOS 10.14 or later. If you'd like to try it out, or collaborate on the project, or give me a job, get in touch with me