Revision 1

NPC simulation is the system that runs the daily lives of every resident of Mossport in Witchbrook. Hundreds of named citizens occupy the city with their own appearances, homes, and routines, and they continue moving through their days whether or not the player is around to watch. The system is tiered: a high-fidelity simulation runs for the chunks of the world immediately around the player, and a lower-fidelity simulation handles everywhere else. That structure is what lets the city feel busy and consistent at the same time.

Overview

Chucklefish has publicly framed the city as a real place rather than a backdrop. Each named NPC has a unique appearance and a home of their own, and the simulation tracks where they live, where they work, what they do on a typical day, and how their schedules shift when the weather changes or the calendar advances. NPC schedules respond to seasons, weather, and town events, and the studio has flagged the simulation as one of the longest-running technical investments in the game.

The system intersects with most of the rest of the game's loops. The romance system depends on knowing where to find a candidate at a given time; home consultations send the player into private routines that the simulation is already running; civic witchcraft jobs slot into errands that townsfolk would have done anyway; and the streets stay busy because the simulation keeps citizens, cars, and the bus running on their schedules even when the player is somewhere else.

Two-Tier Simulation

The tiering means a player walking from the college to the harbour passes through the high-fidelity bubble as it moves with them. Wherever the player is, the immediate streets are populated by characters living their full schedules, while the rest of Mossport keeps its broader rhythm running in the background so it lines up the next time the player wanders into it.

Daily Routines

Each NPC follows a routine that places them in expected locations at expected times. Shopkeepers open and close their businesses, students walk to class and back, Eli Ivers splits his time between the editorial office and the College Shop, Hana Sato runs shifts at Calico Fresh Threads, Pip Marin works in her harbour workshop, and Cormac Fitzroy sets up at The Briny Brush or out on the beach. The studio has called those routines out as one of the things they want players to learn over the course of the year. Knowing where to find someone at a given time is part of how the social systems open up.

Routines also respond to seasons, weather, and events. NPCs add scarves in winter, carry umbrellas in the rain, and shift their schedules around festivals and seasonal milestones described in seasonal cycles. The simulation makes those changes consistent across the cast, so the whole city reacts to a change in the calendar rather than only the named characters the player has been talking to.

Traffic and the Bus

Mossport runs a working road network on top of the pedestrian routines. Cars use the streets, follow British road rules, signal at junctions, and yield to pedestrians, and blocking traffic creates real congestion with the simulated drivers honking in displeasure. A regular bus service runs through the city, providing public transit between districts and rotating decoration alongside the season. The street layer is part of why Mossport reads as a lived-in city rather than a static map: the traffic moves whether or not the player is on the road, and the bus arrives on schedule whether or not the player is at the stop.

How NPC Simulation Connects to Other Systems

Related Pages

Mossport describes the city geography that the simulation populates. Seasonal Cycles covers the calendar layer NPCs respond to. Academic Year anchors the student-side routines at Witchbrook College.