RetroArch - RetroArch is a frontend for emulators, game engines and media players.
1BITDRAGON - 1BITDRAGON is a user-friendly music creation software that allows anyone to make music without having to be an expert or have thousands of dollars of gear.
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.
OnlineSequencer.net - OnlineSequencer.net is an online music sequencer that allows users to create beats and music tracks.
Playnite - Source code generated using layoutit.com
GoatTracker - This is a crossplatform C64 music editor.