Gravity

A storyboard panel with a physics world behind it. The paper, the floor and the two people (Ines and Vex, from the lab cast, drawn once by the kit's drawCharacter) are the storyboard; every prop you drop is a matter.js body whose Rough.js drawing follows its position and angle each frame. A prop that lands within 160 px of a character makes them look surprised for a second: the kit redraws them with the same seed, so only the face changes.

What this taught us

1. Physics adds the one thing a storyboard never had: consequence. A dropped key lands where the world says, bounces off the envelope that fell before it, and settles at an angle nobody drew. The panel stops being a picture of a moment and becomes a place where moments happen, and the characters' surprise, triggered by a collision rather than a script, reads as a reaction. Status: promising for a demo, not yet for a storyboard.
2. The cost is a frame loop that never stops. The engine steps and every prop's transform updates at 60 frames a second, whether or not anything is still moving; the readout shows the time a frame takes. The characters stay cheap because they are drawn once and only redrawn (a few dozen Rough.js paths each) when a prop lands near them; redrawing them every frame would cost more than the whole physics step. The panel also stops being reproducible: the same drops never pile the same way twice unless the engine is stepped on a fixed clock, which this page does.
3. A storyboard could carry a "drop" action as data: { action: "drop", prop: "key", x: 0.3, at: 1.2 }, with the kit's prop drawing and a body of the same size, and the panel's still picture as the state after everything has settled (the reduced-motion path here does exactly that: it steps the world 300 times and draws the result). What it cannot carry is the exact pile; the author gets to choose what falls and where, not where it ends up.
4. The kit's props are not exported as functions, so the key, envelope and padlock here are redrawn by the page in the pack's proportions; a kit release that exports its prop drawings (and a size for each, so a body can match) is the thing to lift. The surprised face needs the kit to redraw the whole character; a mood that could be swapped on a drawn character would make the reaction a two-line change instead of a redraw.