Where the Engines Live

Every session needs a body of rules and instincts the master runs. In SPAECIMH those live in prose files under /GM Instructions/ — and deciding what belongs there versus in the Player's Handbook versus in a structured data file is a judgment every builder keeps making.

Three homes, three readers

A fact about the system ends up in one of three places, depending on who may read it:

• Player's Handbook (/handbooks/player/) — how the rules work at the table. Public. Every player reads it. This is where "how do I roll a check" belongs.
• Builder's Manual (this book) — how to build on the system. Fellow creators read it. That's why this chapter is names-and-intent, not flavor.
• GM Instructions (/GM Instructions/) — what the master runs during play and keeps secret from players. A private, operational layer the master agent loads, not a handbook any player opens.

The engine files: what's actually there

The default world ships three GM Instruction files. Their split is intentional and worth imitating:

• 00 — Master System. The immutable core: attributes, ORIGIN tiers, the 4d6 check, combat, economy, Karma, Fate Points, Acts, Awakening, anti-cheat. This is the rules that never bend. Note how it states both the mechanics and the tone ("strict but fair Master; the illusion of freedom in a world of immutable laws").
• 01 — World Simulation & Narrative Engines. The invisible machinery: Director AI layer, Story Gravity, Cinematic Hook, narrative pressure, escalation, world state tracking, factions, world drift, memory anchors, myth formation, NPC activity.
• 02 — Nine Genre Opening Scenes. Nine read-aloud openers (fantasy, cyberpunk, sci-fi, apocalypse, horror, noir, western, mythic divine, subterranean). Each is a ready drop-in starting scene keyed to the same location architecture.

What belongs in GM Instructions and what does not

Belongs: secrets and twists the players must not see; adjudication rulings (how the master decides difficulty modifiers, when Karma shifts); escalation instincts; the engines that run invisibly behind the scene. This is the master's private operator's manual.

Does not belong: a re-statement of rules the players are allowed to know (that's the Player's Handbook's job — don't paste it twice), and anything that is really data. A faction's goal is data → a structured entry; the instruction to run factions is GM prose → GM Instructions.

The split test mirrors the whole system: if a player would read it, it is the Player's Handbook; if only the master should, it is GM Instructions; if it is a thing to search and reference, it is a data file.

The engine list lives in the Master System

The opening line of the Master System commands the sequence of engines to lead every scene — Opening Creator → Character Sheet System → Cinematic Hook → Threat Vector → Narrative Pressure → Dynamic Faction → World State → Scene Escalation → Character Arc → Director AI → Memory Anchor → Story Gravity. When you write new GM Instructions, keep that engine vocabulary consistent. Inventing a new "System" that collides with one already named, or adding one that breaks the ordering, fragments the master's playbook.

A caution on scope

GM Instructions are operational, but they are not unlimited. They should steer how the master runs — not attempt to out-write every possible moment. The moment a GM Instruction becomes a script for one specific scene instead of an engine for running scenes, it has become data and belongs elsewhere. Keep the instructions at the altitude where they generalise; the nine openings are the models for how specific you may get, and they too are intended as launches the world then drifts.

If you keep the three homes distinct — public rules, private engines, searchable data — the system stays coherent no matter how much you add to it.