There isn't a single emulator but there are lots of very good dedicated emulators for G&W and a lot of the other early 80's tabletop videogames that run in skins of the original cases etc.
Strictly speaking theuy aren't emulators since the directly include the original game code (which breaches copyright and therefore the AUP at this site) however try googling 'Madrigal Tabletop Games' you just might stumble across something interesting.