LaunchBox - LaunchBox is a portable, box-art-based games database and launcher for DOSBox, emulators, arcade cabinets, and PC Games. Download it free!
RetroArch - RetroArch is a frontend for emulators, game engines and media players.
GameEx - GameEx is considered to be the most powerful and feature rich front-end for MAME, GameBase, Daphne, PC Games and all command line based game emulators, along with being a complete Home Theatre PC solution.
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.
GamersGate - Buy and download games instantly for PC and Mac.
Playnite - Source code generated using layoutit.com