A Falling-Sand Sandbox With Fire, Water, and Lava

A free falling-sand game that runs as a live physics sandbox in your browser. Paint sand, water, fire, lava and more onto the canvas and watch them interact: water turns lava to stone, fire spreads through wood, acid eats solids and plants grow into puddles. There is no goal — just an endless toy to experiment with.

How to Use the Sandbox

Pick an element

Choose sand, water, fire or any other element from the picker, or the eraser.

Paint on the canvas

Click and drag to drop your element. Larger brushes pour more at once.

Watch it react

Elements fall, flow and react. Try water on lava, or fire next to wood.

Save your sandbox

Use Save PNG to keep a snapshot, then Load PNG to bring it back later.

Drop sand, pour water, and watch elements react in real time

Load PNG

Brush size

Simulation speed

Brush shape

Colour palette

Features

Fourteen elements — sand, water, fire, lava, oil, acid, plant, ice and more Realistic reactions: water and lava form stone, fire spreads, acid dissolves solids Adjustable brush size and shape, plus pause, single-step and clear controls Save the sandbox as a PNG snapshot and load it back to continue later Stable physics on a fixed timestep with adaptive resolution to keep 60 FPS

Frequently Asked Questions

How do the elements interact?

Each element follows simple physics rules. Water flows and douses fire, lava ignites wood and hardens into stone when it meets water, acid dissolves solids, and plants grow into nearby water.

Why did the resolution change?

The sandbox runs a fixed-timestep simulation and watches the frame rate. On a slower device it coarsens the grid a little so the physics stay smooth at around 60 frames per second.

Can I save what I made?

Yes. Save PNG exports the whole sandbox as a small image. Loading that PNG back rebuilds the exact same arrangement of elements so you can keep experimenting.

Is there a way to win?

No — it is a sandbox, not a game with a score. The fun is experimenting: build dams, start fires, carve caves with acid, or just watch the sand pile up.

Does it work offline?

Yes. The whole simulation runs in your browser with nothing to install, so once the page has loaded the sandbox keeps working without a connection.

💡 Want us to improve this tool just for you?

We can — and it's free! Just send us a quick message with your idea. If you'd like to discuss it in detail, leave your email and we'll get back to you. You can stay anonymous.

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Who is this tool for?

🎮 Gamers 🎓 Students

Published 18 May 2026 Updated 30 May 2026