dreamOS is a series of UI mockups for the ideal desktop operating system that can also adapt to other kinds of devices.
It features its own Plasma design language, inspired by Windows 10, macOS, Chrome OS and Android. In the many mockups you’ll see many apps such as a file manager, a mail client, a music player, a settings app and more.
These mockups are only to show what an ideal OS would look like.
You can also see this design on Dribbble.