BallEngine

Falling Sand:
Elements that react on their own

Sand sinks through water, oil floats on it, fire takes the oil and flashes the water to steam. Nothing is scripted and the biggest moments are the ones nobody placed.
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A frame from Falling Sand
Open the studio to run this mode live.

Falling Sand is being built right now

The engine, the physics and the look are done enough to watch. What is not finished is everything around them: the settings, the presets and the export path. So we shipped it as a preview instead of sitting on it.

The order is decided by these votes rather than by us, and the most-voted modes go first. If this is the one you want, say so.

What you can do now
Open it in the studio and watch a full run, with sound, exactly as it stands today.
What is held back
Settings, randomize and export. The preview runs on our defaults so every viewer judges the same version.
When it ships
The most-voted unfinished mode is the one we take next.

What Falling Sand does

Sand, water, oil, fire, plant and stone pour into the arena and react with each other until the whole thing fills.

Falling Sand is not ball physics. It is a coarse-grid cellular automaton, the falling-sand toy people have been losing hours to for twenty years, wired into the studio so it can be shot as a video with sound and exported like any other mode.

Elements pour in from emitters at the top and behave the way you expect them to. Sand sinks through water. Oil floats on it. Fire burns oil and plant, and flashes water into steam. Steam rises and condenses back into water. Plant creeps into water and spreads. None of it is scripted; the reactions come out of the rules.

The payoff is watching a cascade you did not plan. A pocket of oil finds a flame twenty seconds into a run and a third of the arena goes up. Then the arena fills, the run holds on the finished image, a payoff sound plays, and it resets.

How a run plays out

The exact sequence the engine runs in this mode, from the first frame to the moment the run resolves.
  1. 1.

    Emitters pour from the top

    Elements enter the grid from emitters along the top edge. Beat Spawn ties those emissions to the music so material arrives on the beat rather than continuously.

  2. 2.

    Cells fall and interact

    The grid is stepped once per frame. Sand sinks, water spreads, oil floats, fire burns what it can reach, steam rises and condenses. Every interaction is a local rule between neighbouring cells.

  3. 3.

    Reactions cascade

    Because the rules are local, a single flame reaching a body of oil sets off a chain that runs as far as the fuel does. The largest events in a run are the ones nobody placed.

  4. 4.

    The arena fills and resets

    When the grid is full the run holds on the finished image, plays the payoff sound and auto resets. The final frame is the artwork the run produced.

Every control in Falling Sand

These are the settings this mode adds on top of the shared physics, visual, audio, and export controls. Names match the studio sidebar exactly.

Elements

  • Elements
  • Water
  • Oil
  • Fire
  • Plant

Each element can be switched in or out. The interesting runs come from combinations rather than from any one element, and oil plus fire is the pairing that produces the biggest cascades.

Grid and arena

  • Grid
  • Stone Floor
  • Show Arena Frame

Grid resolution is the trade between detail and speed of filling. A stone floor gives the material something to pile against instead of settling flat.

Sand art

  • Mode
  • Sand Art
  • Picture
  • Reveal Order

Sand art mode pours the grains so that they assemble into a picture. Reveal Order decides whether the image builds top to bottom, outward, or in a scatter that resolves late.

Timing and audio

  • Beat Sync
  • Beat Spawn
  • Beat Element
  • Follow Song Timing
  • Payoff
  • Reaction (fire / sizzle)
  • Payoff (arena full)
  • Override Global Audio

Beat Spawn is what turns a physics toy into a music video: material arrives on the beat, so the fill is rhythmic rather than a steady pour.

Why Falling Sand videos hold attention

What keeps people watching this mechanic.

Chain reactions are unplanned events

A fire finding oil is a big visible moment that nobody scheduled. Runs produce their own highlights, which is why the format survives repeat viewing.

Filling is a visible progress bar

The level rises. Anyone can see how far through the run is and roughly how long is left, which is a strong reason to stay for the finish.

The material is legible without explanation

Everyone already knows sand sinks and fire burns. There is no rule to teach, so the video starts working immediately.

The last frame is a picture

Runs end on a settled composition rather than on motion stopping. That final image is what gets screenshotted and shared.

Videos you can make in this mode

Each of these is a different configuration of the same mode, so one setup session produces a batch of related uploads.

Full element mix

Everything switched on and left to run. The most chaotic version and the one most likely to produce a cascade worth clipping.

Fire and oil

Just those two plus sand. Long quiet stretches punctuated by very large events.

Sand art reveal

Sand art mode with a picture and a slow reveal order. The video is a drawing assembling itself out of falling grains.

Beat-spawned pour

Beat Spawn on with a strong track. Material arrives in pulses and the fill is visibly rhythmic.

Water and plant

Plant creeping through water fills the arena slowly and organically. The calmest version of the mode.

Layered pour

Set the beat element to change between sections so the arena fills in distinct visible strata.

Make your first Falling Sand video

The order that works. Following it out of sequence usually means retuning settings you already set.
  1. 1.

    Open the mode

    Start in Falling Sand and let one run fill completely before changing anything, so you know the base pace.

  2. 2.

    Choose the elements

    Switch on the ones you want reacting. Fewer elements make a run readable; more make it chaotic.

  3. 3.

    Set the grid

    A finer grid gives more detail and takes longer to fill. Match it to the runtime you want.

  4. 4.

    Sync to the track

    Turn on Beat Spawn and pick the element that arrives on the beat, so the fill has rhythm.

  5. 5.

    Watch the finish

    Check that the arena fills to a settled image rather than stalling with gaps. Adjust emitters if it does.

Settings that make the difference

  1. Oil and fire together produce the biggest single events in the mode. If a run feels flat, that is the pairing to add.
  2. A stone floor gives material something to pile against, which produces far more interesting shapes than a flat settle.
  3. Beat Spawn is what separates this from a screensaver. Rhythmic arrival makes the fill feel authored.
  4. Sand art mode is the version most likely to be shared, because the finished frame is a picture rather than a pile.
  5. Every spawn and coin flip comes from the seed, so a run you like can be reproduced exactly, including in an offline render.

What breaks a run

  1. Switching every element on at a fine grid resolution. The arena becomes visual noise and no single reaction reads.
  2. A grid so fine the arena never fills inside a watchable runtime.
  3. No fire in a run with oil, which leaves the most reactive material in the mode sitting there doing nothing.
  4. Ignoring Beat Spawn, which gives up the only thing tying the visual to the soundtrack.

A grid, not a physics engine

Nothing in this mode is a rigid body. The arena is a coarse grid of cells, each holding an element, and the whole grid is stepped once per frame with local rules: this cell falls if the one below is empty, this one burns if a flame is adjacent, this one rises if it is steam.

That has a practical consequence for what the mode can show. Because a cell only ever consults its neighbours, the cost is proportional to the grid rather than to the number of particles, so a hundred thousand grains cost what a hundred thousand cells cost and nothing more. The whole grid is drawn in a single blit from a small offscreen canvas rather than as a hundred thousand individual draws.

It also means the emergent behaviour is real rather than authored. Nobody wrote a rule that says a fire will hollow out a pocket of oil and drop the sand above it. That is what the local rules do when you put those three elements next to each other.

Making the fill rhythmic

Left alone, the emitters pour continuously and the arena fills at a constant rate. That is fine as a toy and dull as a video, because a constant rate carries no information and gives the eye nothing to anticipate.

Beat Spawn ties emission to the music. Material arrives in pulses, so the level rises in visible steps and the run has a pulse that matches the track. The element that arrives on the beat is selectable, which means the beat can be sand for most of a run and fire for a chorus.

Because every spawn position and every coin flip in the automaton comes from the configured seed, this stays reproducible. A run that produced a spectacular cascade can be rendered again offline and it will produce the same cascade, which is the difference between a lucky recording and a repeatable format.

Falling Sand questions

Modes that pair with Falling Sand

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