SM Choukyoushi Hitomi Bangai Hen is an unlicensed hentai game made originally for the SNES. It's a bit simple by today's standards, but it's the only true sex game for the system. I was amazed that there was no gameplay of this game anywhere on the internet other than a couple people who couldn't figure out how to get past the age restriction check. My Japanese is rusty, so I didn't manage to get super far after that and the first H scenes, but I wanted to at least capture gameplay footage of it that wasn't the menu.
https://www.xvideos.com/video46217773/too_hot_for_nintendo._snes_sex_game_sm_choukyoushi_hitomi_bangai_hen_2