I used to be huge on building NPC ai, but I don't think that's what you're looking for : )
Viewing post in Looking for a list of very AI-heavy games
it doesn't carry over very well actually, sure you can jam an LLM in your game but it will just constantly hallucinate and get everything wrong, you won't be able to tune it into a narrative, it will break character easily etc, etc. in my opinion at this stage and probably future stages it won't have a very big inpact on specifically npc ai, maybe maychine learning could be useful for meadow pathing but that's about it, and that wouldn't be new.
You mean like Yandere AI Girlfriend Simulator. There's a ton of videos about that.
There is also discussions about how that would not be a very good idea for classical npc usage for various reasons. The ai, as the word used to be used for what npc do in a video game, does not benefit all that much from what llm gen ai can do. Or maybe they do, but it is used at a much, much smaller scale. It sure would make 4x games more interesting and other types of games where you play against ai players.