There are a few that are actually fun as games, Tifa Tanx2 being the only example that comes to mind, it’s a fun Kung Fu (NES) like beat’em up with easy combos. There are even some work-safe gameplay videos of it on YT

A lot of the games are visual novels, this is where you find a decent variety of styles, though a lot of them use daz3d models, which I don’t like. I’d wager that hentai games are like 60% VNs, 30% RPG Maker, 10% everything else