Johnw1104 on 11 January 2018
We've really only seen games being routinely ported to both gens over the last half decade or so, mainly because the leap in hardware from one gen to the next was comparably small this time around as far as visuals and such are concerned... for most of It certainly seems possible that this is the only time that has happened.
The only instance I can think of where this probably happened was Pac-Man for the Atari 2600 (confirmed top seller) and Pac-Man for the Atari 5200 (probable top seller), but I'm not sure that should count as the latter isn't a port of the 2600 version but was built from the ground up as the 2600 version was notoriously flawed.
