This is probably from the Second Chance pool.
https://github.com/minimaxir/hacker-news-undocumented?tab=re...
It's an amazing little OS and you should try it as a glimpse of something mature, capable and useful that is entirely outside and separate from the Unix/Windows/DOS/Mac/C-language tradition. It's as unique as a mainframe OS or something, and yet it's a tiny fast graphical desktop.
Other discussion: