ScummVM - Game engine recreation of SCUMM made by LucasArts.
RetroArch - RetroArch is a frontend for emulators, game engines and media players.
DOSBox - DOSBox is a DOS-emulator that uses the SDL-library.
mGBA - mGBA is an open source emulator of the Game Boy Advance. The goals are speed and accuracy.
ePSXe - ePSXe (enhanced PSX emulator) is an emulator of the PlayStation video game console for x86-based PC...
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.