Someone showing off their uniquely styled desktop. Usually showing multiple panes, one of which is an empty desktop and some apps in another to show the background and window styles. If you are used to things close to the Gnome/KDE/Cinnamon default looks and are confused, they did a good job!

River is a tiling window manager FYI.

The “dotfiles” contain all the relevant config. Most of it is in ~/.config usually