Edit: It's probably just easier to mark our private repository as public for today. It contains copyrighted material as well as some assets from commercial games we use for internal testing so I'm essentially leaking an internal codebase, but we just don't have enough eyeballs on this for it to matter. I'll mark it private by the end of the day.
Keep in mind the main branch is probably broken from our experiments with uplifting the UI to use Yoga. CSS 2.1 and Flexbox are on the product backlog, but I may end up ditching Yoga since it's becoming too much of an engineering time drain. Feel free to git bisect it until you find the working commit. My apologies.
That being said, the Planimeter/game-engine-2d repository is only a few major features behind this branch.