Characters act.
The world reacts.
Between chapters, the simulation runs. Relationships evolve. Power shifts. When you open the next chapter, the world has moved — without you typing a word.
What simulates
the modelAfter every chapter, the world moves.
A "world tick" runs automatically when you complete a chapter. The engine evaluates every entity's state, applies the consequences of what happened in the story, and advances each relationship, power balance, and economic factor by one step.
Tick depth is configurable — a light simulation tracks only character relationships; a deep simulation runs faction politics, economic flows, and cascading event chains simultaneously.
Your AI always reads the current world.
When you generate Chapter 5, the Prompt Engine reads the entity states as they stand after the Chapter 4 tick — not as they were at the start of the book. Characters are tired or emboldened. Factions have gained or lost. The world has aged.
Stories stop feeling frozen. Characters start surprising their authors because the simulation occasionally resolves tension in ways the engine — following the logic of the world — makes inevitable.
New story arcs unlock automatically.
The simulation watches for threshold crossings. When a character's health falls below a limit, succession arcs unlock. When a faction's power exceeds a rival's, conflict arcs emerge. These aren't scripted — they're emergent from your world's own logic.
You're alerted, not forced. Unlocked arcs are suggestions. Take them, ignore them, or use them as inspiration for something else entirely. The world generates its own plots; you decide which ones get told.
Works best alongside
related featuresA world that breathes
hero planLiving World simulation is available on the Hero plan. Start free, build your world, and upgrade when you're ready for the world to start surprising you.