Some combo system. The NPC's are like skyrim, on rails with some randomness so it gives the illusion of being alive, but when the user interacts with them, the AI takes over and fleshes them out to give them life and when you leave them they revert back to what they were, perhaps with some modifications to their rules and behavior depending on what the user did. The AI could also randomly take over NPC's to generate interesting things for the user to see or generate quests for the user. The potential is there, just going to take some trial and error to figure out what works and doesn't.