A living physics sandbox where you invent the matter and the rules.
Sand Pit Online is a falling-sand simulator with a twist: you define the physics. Create substances, make them interact, and watch the chemistry evolve. Build entire systems within Pits, then share them for others to see!
No account needed to start pouring.Design
Dial in weight, density, viscosity, and color to make anything from heavy molten metal to a wisp of floating gas. Add thermal and electrical conductivity to wire up heat and current.
Simulate
Watch a real-time cellular automaton settle your grains under gravity, then author chemical interactions that turn reactants into products — fire, decay, crystallization, and beyond.
Save & share
Snapshot an entire board — every grain, substance, and rule baked in — as a Pit. Share it so anyone can open your world and poke at it, exactly as you left it.
Explore!
Browse a growing public library of substances and Pits built by other tinkerers. Download the ones you like, remix them into your own experiments, and star your favorites.