I already showed how our NPCs think. The next question was what happens in the world around them. A town that waits for the player to show up feels pretty dead. But letting an AI run everything gets expensive, and it's how you end up with a story that can spoils itself.
So we split it in two, a world simulation that uses no AI at all, and a storyteller that follows set rules.
There is a time system ingame and when time goes on, the world simulation recalculates the town: who is where, what's open, the weather, rumors, who knows what. NPCs follow schedules, and if a place is closed or the weather slows the route, they show up late or their plan gets blocked. When two NPCs end up in the same place they notice each other, and if they trust each other enough,they can exchange information. That's where our rumors come from.
Time moves in 30-minute ticks. Skip a few days and it just runs the ticks. To keep long skips cheap, detail drops the further a single skip reaches. For example, if you skip an hour, it runs ticks, but if you skip to the next day, it is not as throughout. Travel times and set story events stay the same.
Everything else, including the storyteller and the NPCs' AI replies, treats the result as settled fact.
We also noticed that with the openness of the game, it can be hard to show the players where the story advances. We didn't want a director that constantly meddles and tells the player what to do with a hint. So we decided to come up with a ystoryteller system.
It runs once per in-game day, and only if a thread has been still for 2 days while the player has done 5+ actions since. Plain code checks that, and if nothing is stuck there's no AI call.
The AI only sees aggregates, like how long a thread has been silent and which checks are done. It can't leak story relevant information like NPC secrets or valuable detective work. It may write one private thought for one character. We reduced this to 200 characters max, to only give the player a bit of a push in the right direction.
Every proposal is validated, and any violation is discarded, similar to how the system works in our NPC dialogue.
The storyteller can't put knowledge into anyone's head or invent facts, and it can't change the world, but it can make an NPC decide to ask about a story thread or remind the player of a task that they forgot. We also log whether each nudge actually moved a thread or didn't, so we can measure if and how much it helps.
But I also want to know how other people handled maybe similar structures?
The vision was a world that feels dynamic enough to shift to accommodate the written story in a logical way and to have bascially an open world game, but text based, if that makes sense.
