skiftOS: a hobby operating system
skiftOS is a hobby operating system built for learning and for fun targeting the x86 platform. It features a kernel named hjert, a graphical user interface with a compositing window manager, and familiar UNIX utilities.
This looks remarkably advanced for a hobby operating system", and can be run in both Qemu and VirtualBox. This one is definitely worth a virtual boot. The code is licensed under the MIT license and available on GitHub.