Skyrim, FO3, FONV, and FO4 were all fun modded. Skyrim had the best adult mods, but FONV had my favorite ones for gameplay. Like a fully VA'd follower you could have sex with.
Some random NGE VN when I was like 15 or 16 way back in the dark ages. Never finished it, may still have it somewhere on my hard drive all these years later.
Photo Hunt is probably one of my favorites, technically written into the intro to be inseki BUT there is a fan mod to remove that line or you can just ignore it. The rest of the game as written as if they were blood related.
This is legitimately one of the best games out there. It can be a little grindy at times, but the renders are amazing, the characters greats, and the stories actually interesting. I adore Rachel.
AI is bad, not the technology but the current implementations. They are built using stolen art, which is bad for everyone. It can never create something truly new, only steal bits of other peoples work to cobble together something that appears new, and often not very well.
As for use in games...
You know one that just completely poofed? Ecchi Sensei. Like, it wasn't good. Had way too much going on and was kind of a mess, but I was interested in seeing where the father was going to go. They said they would compile the existing parts into a single app and then were never heard from again.
Completely smooth for sure, like if its a small and well trimmed bush I won't be grossed out but a forest is a big no thanks. Goes for males to to be honest.