Thanks for the question!

The motivation came from building desktop applications and working with awesome but cumbersome GUI toolkits like Nuklear.

I built a graphics backend-agnostic GUI library in CRuby called Hokusai, but Hokusai uses FFI, isn't portable, and is hard to distribute. (Need a Ruby interpreter on the target)

I ported the library to MRuby, developed some build tools, and now have a portable binary for different platforms that can run a dynamic desktop application/game that is written in Ruby.

You can try it yourself by downloading the latest release and running an app like: https://github.com/skinnyjames/hokusai_demo_paint

If you notice the paint repository, there is nothing to build, just ruby scripts and assets.

The tool also has commands to build your application for different platforms as standalone binary, but I'm currently working in that space for other reasons.

There are of course constraints to using MRuby vs CRuby, but I hope I speak to how this library addresses those.