Reference
Falling Sand Game Elements & Reactions
Every material in the falling sand game and how it behaves — powders, liquids, gases, and solids — plus the reactions that happen when two of them meet.
Play the Falling Sand GameThe sandbox ships with fourteen materials plus an eraser. Each one belongs to a family — powder, liquid, gas, or solid — that sets how it moves. What makes a scene interesting is the reactions: contacts that transform one or both materials.
Select a material from the palette on the home page and paint it with a click or a drag.
Powders
Fall straight down, then slide to form a slope. Denser than every liquid.
Sand
The signature powder. Grains fall straight down, then tumble diagonally to form a natural angle of repose. Sand is denser than water and oil, so a stream poured onto a pool sinks to the bottom and builds a bar.
Stone
Stone behaves like coarse gravel: it falls and settles but almost never slides diagonally, so it holds near-vertical columns. Lava that touches water also freezes into stone.
Salt
Salt falls and piles like a paler, finer sand, but any grain that touches water dissolves and vanishes, slowly clouding and eating the pool it fell into.
Liquids
Fall, then flow sideways to level out. Layer by density.
Water
Water falls, then spreads sideways until it is flat. It floats on nothing and sinks under oil. It quenches fire, turns to steam against lava, dissolves salt, and feeds plant growth.
Oil
Oil is less dense than water, so it always rises to the surface of a pool and spreads into a thin film. It ignites readily and carries flame across a whole reservoir.
Lava
Lava is a heavy, glowing liquid. It ignites everything flammable it touches, radiates heat and smoke, and freezes into solid stone the instant it meets water — the classic way to build islands.
Acid
Acid eats sand, stone, wood, plant, and salt, losing a little of itself with each bite. It cannot touch wall, so a wall-lined basin is the only safe way to store or aim it.
Gases
Rise and spread to fill space. Most fade or transform with age.
Fire
Fire is short-lived. It licks upward, sets wood, plant, oil, and gas alight, boils water into steam, and fades to smoke. Cooling flame shifts from white through orange to deep red.
Smoke
Smoke is the exhaust of fire. It rises, wanders sideways, and dissipates after a few seconds. It does nothing on its own but is useful for reading air currents around a build.
Steam
Steam forms when water meets fire or lava. It climbs, and when it cools — against a ceiling, a wall, or simply with age — it condenses back into a droplet of water, so a sealed boiler will cycle forever.
Gas
Gas billows upward and spreads to fill any sealed space. It is inert until a flame reaches it — then the whole cloud flashes to fire at once. Handle near lava with care.
Solids
Hold their position. Wall is inert; wood and plant burn.
Wall
Wall never falls, burns, dissolves, or reacts. It is the one material acid cannot chew through, which makes it the right choice for tanks, funnels, and the frame around a contraption.
Wood
Wood holds its position like wall but catches fire when flame or lava touches it. It burns longer than plant, throwing embers and smoke, and leaves nothing behind.
Plant
Plant is a living solid. Wherever it sits next to water it sprouts new plant cells, consuming the water as it climbs. It is highly flammable, so a single spark can race along a vine.
Reactions
What happens when materials meet
Lava + Water → Stone + Steam
Pour water onto molten lava and the lava chills into solid stone while the water flashes to steam. Drip it slowly to sculpt land; dump it fast for a cloud.
Fire + Oil → a spreading slick
Oil floats on water and carries flame from end to end. One spark on a covered pool lights the whole surface, then burns down to nothing.
Fire + Water → Steam
Flame touching water is snuffed out, and the water it touched can boil off as steam that rises, cools against the ceiling, and rains back down.
Plant + Water → Vines
Plant drinks any water it can reach and grows new plant into the gap. Trap a plant seed between a puddle and open air and it will climb on its own.
Acid + Solids → Nothing
Acid dissolves sand, stone, wood, plant, and salt, wearing itself down as it works. Only wall survives, so line an acid tank with wall.
Salt + Water → a cloudy pool
Salt grains that land in water dissolve and disappear, thinning the pool. Rain enough salt and the water is eaten away entirely.
Gas + Fire → Flashover
Gas is harmless until a flame reaches the cloud — then every cell ignites at once. Fill a room, then light a match at the door.
Sand + Water → a sandbar
Sand is heavier than water, so a poured stream sinks straight through the pool and builds a bank on the bottom instead of floating.