It's kinda like SteamOS, but not. Not managed by Valve, a little more cutting edge, a hair more performant, a hair more customizable, but also immutable, and also very gaming-focused. Comes in flavours for handheld PCs, regular desktop, or home theater gaming PCs, KDE or Gnome, and supports AMD or Nvidia.

Like SteamOS, it's immutable, very beginner-friendly, while also being very open and modifiable like any Linux distro. A strong recommendation for any gamer who's sick of Windows, so it's seen amazing growth.