Theme Vectors — choosing a setting that recolours the mechanics

What it is. The theme is the fiction the mechanics wear — the where, when, and who. It is one of the six twist vectors in process-the-twist, and the cheapest to reach for, which is exactly why it’s the easiest to waste. A theme earns its place when it recolours the systems — makes the same rule mean something new — not when it merely repaints the sprites.

Player fantasy / why it’s fun. A setting is a promise about what the numbers mean. “Fuel” and “faith” can be the identical resource loop; one is a survival horror, one is a pilgrimage. The theme is where the player decides to care.

The test: does the fiction rhyme with the mechanic?

A theme is load-bearing when you can trace a rhyme — a place where the rule and the fiction say the same thing. Skip the theme and the loop still works but means nothing; skip the loop and the theme is a wallpaper. Aim for both saying it.

Mechanic	A theme that rhymes	A theme that’s just a skin
Resource that decays if unused	Grief you must spend before a season ends	”Energy” that ticks down
Territory you can’t hold everywhere	A failing lighthouse network on a drowning coast	Generic “zones” on a map
Permadeath with persistent memory	Orcs who remember every duel (Shadow of War)	Enemies with random names
One-screen constraint	A single tide-pool you tend as the sea rises	”A small arena”

Vectors / options

Theme is a space to choose within, not a single lever. Move along these axes:

Axis	Poles	The mechanical consequence to hunt for
Register	mythic ↔ mundane	Mythic licenses spectacle & absolutes; mundane licenses stakes you feel
Scale	a room ↔ a cosmos	Sets what a “unit” is: a citizen, a hero, an empire, a season
Agency	steward ↔ conqueror	Do you tend the system or bend it? Recolours win conditions
Time	one night ↔ generations	Frames the session container; a run vs a campaign vs a lineage
Tone	dread ↔ cosy ↔ elegiac	The tonal twist rides here; recolours feedback (menace vs warmth)
Material	ink/wood/stone ↔ neon/chrome	Ties directly to `world-aesthetic-direction` and the Regalia set

The Hayao example corpus leans toward one corner of this space on purpose: mundane-register, small-scale, steward-agency, elegiac worlds carried by an ink line and a warm accent. That’s a house lean, not a law — see the aesthetic hook below.

Method

Start from the signature mechanic, not the setting. Name the one rule the game is about (from process-the-twist). The theme has to serve it.
List 4–6 candidate fictions the mechanic could wear. Force range: one mythic, one mundane, one cosy, one dreadful. Don’t stop at the first.
Find the rhyme for each. For every candidate, write the single sentence where the fiction and the rule say the same thing. No rhyme → cut it.
Trace the recolour across three systems (economy, threat, progression): does the theme change what a choice feels like? A theme that touches only the art layer is a skin — send it to world-aesthetic-direction and pick a deeper one.
Check it against the pillars (process-pillars). The theme that most sharpens a pillar wins; a theme that fights one is a different game.
Name the world in one line. “A drowning coast where the last keeper rations light.” If it’s boring to say, it’ll be boring to inhabit — hand the line to world-worldbuilding-scaffold.

Worked example

Loop: a push-your-luck resource run — bank early for safety, press on for more, lose it all if you overreach (pattern-risk-reward).

Candidates: deep-sea salvage; a tea ceremony under time pressure; a wildfire-line dig; a lantern-lighter walking a mountain path at dusk.
Rhyme found: the lantern-lighter. Each lit lantern is banked progress; the dark ahead is the press. Oil is the run’s only currency; the summit shrine is the bank. The fiction is the risk-reward curve.
Recolour: threat becomes the encroaching dark (a timer with a face); the “bank” becomes turning back, which the fiction makes a real cost, not a menu button. Progression is the path itself.
World line: “A lantern-keeper climbing into the dusk, deciding how far the light will reach before the dark takes the path.” (This is the house register’s neighbourhood — arrived at from the mechanic, not copied from it.)

Aesthetic hook

The house look is Regalia (REGALIA, REGALIA_DAY, REGALIA_NIGHT in docs/API.md; see world-aesthetic-direction). Its core-of-four — gold (marks, joy), ink (line, structure), green (growth), blue (sky, calm), grown by the job with rose (vitality) and bark (wood, earth) — reads as bold, warm, hand-drawn craft, so themes in that register (folk myth, seasonal ritual, quiet stewardship, weathered wood and ink) come pre-harmonised. A neon-cyberpunk or candy-arcade theme fights the palette; if your mechanic truly wants it, say so early and swap the palette deliberately — Regalia is a starting point, not a cage (docs/CONVENTIONS.md). But a theme chosen near the house register gets its art direction and its AA guarantee (npm run palette) close to free.

Traps

Skin, not recolour. If the theme could be swapped for another with zero mechanical change, it’s set-dressing. Bend deeper or pick a vector other than theme.
Theme-first tourism. Choosing “steampunk” because it’s cool, then bolting a loop on. The mechanic picks the theme, not the reverse.
Register mismatch. Cosy art on a punishing loop (or dread art on a gentle one) confuses the promise. Let tone, mechanic, and palette agree.
Over-lore. A rich setting with no mechanical rhyme is a wiki, not a game. Minimum viable lore only — world-worldbuilding-scaffold.
Fighting the palette by accident. Reskinning to a clashing world without swapping REGALIA_DAY/REGALIA_NIGHT yields muddy, off-brand frames the JUDGE flags.

Composes with

process-the-twist — theme is one of the six vectors; this module is its deep dive.
world-worldbuilding-scaffold — the chosen setting becomes a coherent world with rules and stakes here.
world-aesthetic-direction — theme sets the register; this turns it into a concrete, JUDGE-passing look.
process-pillars — the pillars are the scoring function for candidate themes.