What are some other genres do you think have the unexplored potential as hentai games?
Any single genre that permit to have a story or to insert sex animations. So, all of them...
Beat'm'up and hack'n'slash can perfectly replace weapons by groping, and have the opponents lying in lust agony when beaten, while the boss would end being fucked, or fucking you depending how good you are.
It's been two decades that platform games have a "fucked on loose" adult variation.
FPS can perfectly be about a prostitution ring defending it's territory and fighting against the cops, with cut scenes interactive and full of sex. Like you can perfectly have a Call of Duty like where you don't just kill the bad guys, but also rape their women, or go to the local brothel for a bit of comfort between two battles.
And so on.