Mundus is a world you build with links, not a single document. Every region, location, home, character, faction, piece of gear, and vehicle is one file, and the files point at each other by slug. The world reads like a web: pull one thread — a character's home, a faction's key member, a location's region — and the adjacent files are already there. This chapter is about how that web is put together, so additions land cleanly instead of tangling it.
How the world is stored
Content lives in folders named for their type: /Regions/, /Locations/, /Homes/, /Characters/, /Factions/, /Gear/, /Vehicles/. The file type is stamped in each filename (The Daily Grind.location.json), and the type's schema defines its fields.
The geography nests downward. Regions carry a parent field: Mundus (world) → Novus (continent) → Alden (country) → Nova Arlington (city) → neighborhoods as Locations. A Location names its region; a Home names its region and neighborhood. A Character names one home, one vehicle, an inventory of gear, and a cast of other characters with Bond, Trust, Type, and Status. Factions name a region, a headquarters location, and their keyMembers as characters.
The rule that keeps all of this coherent: references are written as slugs, not names. jordan-reeves, not "Jordan Reeves." A slug survives a rename — the display name can change and the link holds. When you introduce a new file, the slug is just the name lowercased with spaces turned into dashes.
The knowledge ceiling
Every character file has a notes field. Treat it as the ceiling of that character's awareness — what they know, what they suspect, and what they do not know yet. The GM's knowledge audit runs on this field: an NPC states what their notes contain and nothing more, filtered through Bond and Trust. When you add an NPC, write their notes like a dossier: what they know, what they're hiding, and what would surprise them. A secret in one character's notes is not public information anywhere else.
Adding a character
A character needs three required fields: name, background, and pronouns. Everything else follows a consistent budget:
- Stats — six stats, each starting at 1, with 12 points to distribute. Total is 18; no stat exceeds 5.
- Skills — six skills from the list in the Core Rules, each starting at 1 with 4 bonus points. No skill exceeds 5.
- Archetype — one of the eight. Copy the Unique Ability and Built-in Flaw wording straight from the Archetypes rules sheet; the flaw is story fuel, not flavor text.
- Vitals — Health starts at maximum (10 + Resilience), Stress at 0.
- Computed fields —
maxHealth, maxStress, weeklyNet, and statPointsRemaining are derived; do not write them, change their inputs.
Prebuilt characters may exceed the custom budget. They are established lives with history, not freshly rolled sheets — leave them as they are.
Every character should answer two questions before you save the file: what do they want, and what do they know — or not know — about the Carraway Group or the local Strangeness? The answers give the story a door.
Adding a place or a faction
A Location earns its place with a type, its region, a Strangeness Level from 1 to 5, and the practical texture of the place: services, opening hours, what you can do there. The Strangeness Level is a dial — the Strangeness Rules explain what each level pays out when someone pays attention. A Home adds comfort (which drives recovery), monthlyCost, and the neighbors who make it a place.
A Faction needs a region, a factionType, an influence rating, goals, secrets, and keyMembers. A faction is not a single mind: its members should disagree about tactics, risk, and what they owe one another. The most useful secrets are the ones that would split the faction if they came out.
Running a campaign
A campaign in Mundus is three things working together:
- A Game Start — the lobby card players pick, plus its play configuration: starting location, playable characters, and the opening beat.
- A Campaign Packet (GM Reference) — the promise, the clocks, the faction behavior, and session-sized hooks. Clocks are the backbone: each one advances when the players lose time or let a faction act unopposed.
- The living world — the characters, locations, and factions the packet points at. If a packet names a recurring NPC, that NPC should get a character file, so the knowledge ceiling applies to them too.
Rules of thumb
- One canonical source per rule. The Core Rules are the authority; the GM references and handbooks summarize them. If a number drifts between documents, the fix is the canonical file, not the summary.
- The Strangeness is never explained. Not in a rules doc, not in a location, not in an NPC's mouth. Locations carry a level; the rules describe what noticing reveals. Resist the urge to systematize it — the moment it has rules, it stops being strange.
- Add what the world needs. A new location earns its file when scenes keep returning to it; a new faction when two factions aren't enough to make the politics real. The web is strongest when every file has a reason to exist and a link to something else.
That is the shape of the world. Everything else is detail — and in Mundus, detail is the point.
