Draw with the elements and watch them behave: sand piles up and sinks in water, water spreads and makes plants grow, oil floats and burns, fire spreads through wood, and lava turns water to steam and itself to stone. A sample scene is already running, so start pouring.
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Brush
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How to use the Falling Sand Game
Pick a material from the palette (or press 1-9). The sample scene is already simulating.
Draw by holding the mouse button or your finger on the box. Keep holding to keep pouring.
Change the brush size for fine details or big floods. Use Eraser to remove anything.
Experiment: pour water on lava, set fire to a wooden bridge, plant seeds by a pond or float oil on water and light it.
Save your scene to come back to it later, download it as a PNG, or press Clear to start from an empty box.
Materials and reactions
Material
Behavior
Reacts with
Sand
Falls and piles into slopes; sinks through liquids
Lava: can melt into glass
Water
Falls and spreads sideways to find its level
Lava: both become stone and steam. Fire: puts it out. Plant: feeds growth. Ice: slowly freezes
Oil
Liquid that floats on water
Fire and lava: burns fast
Lava
Thick, slow liquid that glows
Water and ice: cools to stone, makes steam. Wood, plant, oil: sets on fire. Sand: glass
Fire
Flickers upward and burns out into smoke
Spreads to wood (slow, long burn), plant (fast) and oil (very fast). Melts ice
Plant
Solid; grows into touching water
Burns easily
Wood
Solid; good for walls and bridges
Burns slowly and for a long time
Stone
Solid, never changes
Nothing: safe for walls and containers
Ice
Solid that slowly freezes neighboring water
Fire and lava melt it back to water
Glass, smoke, steam
Products of reactions. Smoke and steam rise and fade
Steam can condense back into water
Experiments to try
Volcano: build a stone cone, fill it with lava and drop water on top to grow a stone crust with clouds of steam.
Oil fire on water: pour water into a basin, add a layer of oil, then touch it with fire. The oil burns, the water underneath survives.
Garden: scatter a few plant cells along a pond's edge and watch them grow across the surface as they drink the water.
Hourglass: draw two stone triangles with a one-cell gap and fill the top with sand.
Glass making: pile sand beside lava and wait; some grains turn to glass.
How the simulation works
The box is a grid of 200 × 125 cells. Every frame the game visits each cell from the bottom row up, alternating left-to-right and right-to-left so nothing drifts one way. A cell can move only into a neighbor that is lighter than itself, which is why sand sinks under water and oil floats on top. Reactions happen with small random chances each frame, so fires flicker, plants grow unevenly and nothing looks perfectly regular. It is a playful model, not a scientific one, but the ideas of density, heat and phase change are real.
Frequently asked questions
What is a falling sand game?
A falling sand game is a sandbox where the screen is a grid of tiny cells, each holding a material such as sand, water or fire. Every frame, simple rules decide how each cell moves or changes: sand falls and piles, liquids flow sideways, gases rise and fire spreads. Together the rules produce surprisingly lifelike behavior. The idea has been popular in browser games since the mid-2000s.
What reactions can I make?
Lava touching water cools into stone and turns the water into steam. Fire spreads through wood, plants and oil and is put out by water. Plants grow into neighboring water. Sand touching lava can melt into glass. Ice slowly freezes water next to it and melts back into water near fire or lava. Steam rising to the top may condense back into water drops.
Why does oil float on water and sand sink?
Each liquid and powder has a density. A falling cell can swap places with a lighter cell below or beside it, so sand (heaviest) sinks through water and oil, water sinks below oil, and gases like smoke and steam always rise. This mirrors real densities: most oils are less dense than water.
How do I save my creation?
Press Save scene to store the whole grid in your browser on this device; Load saved brings it back, even after closing the tab. Download PNG saves a picture of the current frame. Saved scenes stay on your device and are never uploaded.
Why is the simulation slow on my phone?
Every one of the 25,000 cells is updated up to 60 times a second. Most phones handle it well, but older devices may slow down when the box is full of moving liquid. Pausing, clearing some material or turning off Fast mode helps.
Can I use it with a touch screen or keyboard?
Yes. Draw with a finger or stylus; page scrolling is disabled inside the box so it does not move while you draw. On a keyboard, number keys 1 to 9 select the first nine materials, 0 selects the eraser, Space pauses and brackets [ and ] change the brush size.
Are all the tools on FreeToolCabin tested for quality and accuracy?
Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.