Regeneration
Sometimes a player-initiated pin contradicts the Shadow Horizon — not the Western Horizon, but the Shadow Horizon. The innkeeper the engine generated as a Strangers faction loyalist with no family ties turns out to be a player’s uncle.
The Shadow Horizon regenerates. Not from scratch. The pinned node (uncle innkeeper) is now a hard constraint — it crosses from the Shadow Horizon into the Western Horizon the moment it’s declared. Every other observed node is also fixed. The engine re-collapses only the unobserved tiles, propagating from the updated constraint set.
Three Regeneration Modes
Absorb — The new pin fits within the existing Shadow Horizon with no conflicts. Pin and done. This is the fast path and should be the common case.
Local — The new pin conflicts with a small cluster of unobserved tiles. Regenerate that neighborhood. Medium cost, localized impact.
Global — The new pin contradicts something structural: faction power balance, quest logic, settlement identity. Regenerate the entire Shadow Horizon for affected layers. Expensive, rare, necessary.
Settlements Solidify Over Time
Regeneration gets cheaper as a settlement is played in more. More tiles are pinned by observation, fewer are available to change. A metropolis visited by ten different parties might have 70% pinned nodes — most regeneration requests will be Absorbs.
The world hardens into canon naturally through play, not GM fiat. This is why the Guild Wiki matters: it’s the record of what’s been pinned. Every wiki entry is a node the engine can never regenerate.