What it is. One verb that changes the player’s size, and with it what they fit through, what they can reach, and what they crush. Scale is the key; the level is the lock.

Player fantasy / why it’s fun. The same body solves opposite problems — squeeze through the mouse-hole, then loom over the room and shove the boulder. Transformation is legible power: you see the answer before you earn it.

The verb

Press to change tier (or hold to scale analog). Big self reaches high ledges, presses plates, crushes brittle floors; small self fits gaps, hides, moves fast. The lock is always the current dimension.

How it feels / why it’s fun

• Read-before-solve. A too-small gap or too-high ledge reads as “wrong size” — the puzzle statement is visible. See pattern-readability.
• One verb, two silhouettes. Distinct posture per tier keeps state unmistakable mid-jump. See pattern-juice-choreography.
• Reversible. No penalty for flipping size lets players experiment, not fear. See system-grace, pattern-anti-frustration.

Tuning levers

Keep tiers few and named — three legible states beat a mushy dial. Analog only when the fiction demands precision (fitting an exact aperture).

Slots into

• Genres: genre-puzzle-platformer (its home), genre-grid-puzzle (discrete tiers = clean process-composition pieces), genre-metroidvania (size as a traversal key gating regions), genre-precision-platformer (reach coupling as a movement stat).
• Anchors: anchor-braid (a single mutating rule reshaping a familiar space), anchor-portal (spatial key that reads before it’s solved), anchor-katamari (grow-shares-with-the-world literalized), anchor-into-the-breach (fully readable, reversible state you plan around).

Twist seams

• Grow but growing shares mass with the room, shrinking it (emergence) — your gain is the world’s loss: swelling drains a shared scale-budget so the doorway you needed narrows, or the platform under you shrinks out. Turns size into a two-body negotiation. See pattern-emergence, system-emergent-systems.
• Shrink but tiny-you is fast and giant-you is strong (risk-reward) — no dominant tier: small dodges and infiltrates but can’t hit hard; big bulldozes but is a slow target. Every screen asks which weakness you’ll accept. See pattern-risk-reward.
• Grow but only what you’re touching grows (twist: transfer) — the verb scales the object under your hand, not you; the “player” is a size-brush, and the puzzle is choosing what to enlarge. Pairs with mechanic-throw, mechanic-stack.

How it wires to Hayao

• Size is a scalar on the actor’s transform read by the collision extent — start from the physics and camera labs (sandboxes/physics-lab, sandboxes/camera-lab) to see collider extents and follow-zoom in isolation before coupling them.
• Discrete tiers are pure state. Make tier a field of the puzzle state so each configuration is a distinct node — the model of genre-grid-puzzle in examples/sokoban/. Every “does this size fit?” is a deterministic predicate, provable by the solver (see the verify-with pointer above).
• Keep scale cosmetic where it’s only view. The transition tween and squash animate the sprite; the tier is logic, the interpolation is not — split them so the hash tracks only the solved-relevant value.
• Drive size changes through the same deterministic input path as any verb; never sample wall-clock for the tween.

Fails when…

• A dominant tier exists. If big is always better, the verb collapses to “be big” — see antipattern-boring-optimal. Force trade: big can’t fit, small can’t reach.
• Analog when discrete would do. A continuous dial with no readable notches makes the lock ambiguous and the fit fiddly — antipattern-input-lie when a near-fit silently fails.
• Hazards don’t invert. If both tiers fear the same things, size never chooses — you just resize to move, not to decide.
• The size gate is off-screen. If the required tier isn’t legible from the obstacle, it’s antipattern-guess-the-designer. Show the lock’s dimension.
• Transition is punishing. Crushing the player mid-grow, or letting a shrink drop them into a now-lethal gap, breaks pattern-fairness-and-trust — grant i-frames or block the change.

See also

• Traversal siblings that also re-key a space: mechanic-gravity-flip, mechanic-portal, mechanic-teleport, mechanic-clone.
• Composition & proof: process-composition, process-the-twist, system-emergent-systems.
• Feel & fairness: pattern-readability, pattern-risk-reward, system-grace, system-telegraphs.