Ubuntu GamePack - UALinux / Technology of the future - already today
RetroArch - RetroArch is a frontend for emulators, game engines and media players.
SteamOS - We've been hard at work to deliver on our promise of a new kind of living room entertainment environment - one that is accessible, powerful and open. In making SteamOS available to you, we're excited to take the next major step towards that goal.
Playnite - Source code generated using layoutit.com
Linux Ultimate Edition - Ultimate Edition, first released in December 2006, is a fork of https://alternativeto.
Batocera.linux - Batocera.linux is an open-source and completely free retro-gaming distribution that can be copied to a USB stick or an SD card with the aim of turning any computer/nano computer into a gaming console during a game or permanently.