SteamOS

SteamOS is an Linux distribution created by Valve to run Steam games without any extra software. SteamOS 1.0 (released in December 2013) and 2.0 (released in 2015) were based on Debian GNU/Linux and came with the GNOME desktop environment, while SteamOS 3.0 is based on Arch Linux and comes with the KDE Plasma desktop environment. SteamOS 3.0 is designed for the Steam Deck, and later Lenovo Legion Go S, but will soon be available to download and install on any PC or handheld.

Screenshot of SteamOS 3.0, with the default KDE Plasma desktop, running on Steam Deck.

More information can be found on this page.