GameDatum.com - A platfrom of free online games. A list of all the available online free games from various producers online.
RetroArch - RetroArch is a frontend for emulators, game engines and media players.
Mitch - The unofficial mobile app for itch.io
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.
Enjify - Enjify is an online gaming e-store that enables you to buy games for multiple platforms like Nintendo, PlayStation, Xbox, and Steam.
Playnite - Source code generated using layoutit.com