MainOS is a browser based Windows XP clone thing. You can try it here: MainOS on itch.io.
MainOS is inspired by Microsofts Windows XP and other Windows versions. I started MainOS at work, because my boss told me to learn CSS. Since that day I develop MainOS.
If you want to contribute, that would be nice. It's hard to keep up as a single person.
Founder and Leader of MainOS, Primary developer.
He said, his game
Optisocubes may be used in MainOS.
He said, some of his wallpapers may be used in MainOS.