Stella - Stella is a multi-platform Atari 2600 VCS emulator released under the GNU General Public License...
RetroArch - RetroArch is a frontend for emulators, game engines and media players.
WinUAE - WinUAE is a Windows port of the emulator UAE.
LaunchBox - LaunchBox is a portable, box-art-based games database and launcher for DOSBox, emulators, arcade cabinets, and PC Games. Download it free!
jGameBase - jGameBase is a fully-featured retro-gaming emulator frontend and game database utility.
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.