I think the easiest thing would be to sort the remaining games by decade. maybe call it Misc 70's, Misc 80's, etc.
but i think ideally it should be sorted by the manufacturer of the board kinda like https://en.wikipedia.org/wiki/Arcade_system_board not sure if this would actually work though, there might be some games that appeared on various boards.
another thing i noticed is that some games appear in more then one playlist, so that means even less games then i originally thought are actually being sorted.