Falling Sand Game

A falling sand game in your browser

Pour sand, flood it with water, light a fire and watch what happens. This free falling sand game is a physics sandbox where every pixel is a grain of material with its own simple rules. Put enough grains together and you get dunes, waterfalls, forest fires, volcanoes and chain-reaction explosions. There are 12 elements to paint with, an eraser, undo and 8 challenges, and the whole simulation runs smoothly in your browser on computers, tablets and phones.

How to play

1. Choose an element from the toolbar, or press keys 1 to 9.
2. Drag on the world to pour it. Hold still to keep pouring in one spot.
3. Change the brush size with the slider or the [ and ] keys.
4. Mix elements and watch them react: fire burns wood, water and lava make stone, acid eats through walls.
5. Pause with Space to build something carefully, then press play to set it in motion.
6. Try the challenges for small goals, or keep experimenting in free play, which saves automatically.

Element guide

• Sand falls and forms slopes; it sinks through water and oil.
• Water flows sideways to find its level, puts out fire and boils into steam.
• Oil floats on water and burns fiercely.
• Stone never moves: build walls, cups and dams with it. Only acid and explosions damage it.
• Wood is a solid that burns slowly, perfect for trees and houses.
• Plant grows into any water it touches and catches fire easily.
• Fire flickers upwards, spreads to anything flammable and leaves smoke behind.
• Lava oozes slowly, ignites what it touches and turns into stone in water.
• Acid dissolves most materials and is used up as it does.
• Ice slowly freezes water around it and melts near fire or lava.
• Gunpowder behaves like sand until a spark touches it. Then: kaboom.
• Steam rises, drifts and sometimes condenses back into water drops.

Tips and experiments

• Build a volcano: make a stone cone, fill it with lava and add water on the slopes to watch new rock form.
• Make a fuse: lay a thin line of gunpowder or oil to a bigger pile and light one end.
• Grow a garden: place a few plant seeds and drip water on them; plants climb towards the water.
• Hourglass: draw two stone funnels and pour sand in the top for a working sand timer.
• Acid etching: drop acid on a stone wall to carve tunnels and caves.

About cellular automata

Falling sand games are a fun example of a cellular automaton: a grid where every cell looks at its neighbours and follows a few local rules. No grain knows about the whole world, yet waves, dunes and fire fronts emerge on their own. The same idea powers simulations in science and in many famous indie games. If you prefer drawing to simulating, try the free drawing board, animate a doodle in theflipbook animator or relax withcolor by number.