They were on Sega CD, and it was unfortunate that the Genesis Mini didn't include Sega CD games in addition to cartridge Genesis games as the TG16 Mini did. There were quite a few gems on the Sega CD like the Lunar games, Sonic CD, and Popful Mail, which was made by Nihon Falcom. Lunar's licensing is a mess, from a post I read not long ago by the guy at Working Designs who did the localizations, which is why the PS1 versions were never re-released as PSOne Classics.


