256 Rules

Each row of cells decides the row below it. Change the rule and see what grows.

1The rule

Click a tile to change the cell it makes.

2Find the rule

Top row
Arrow keys change the rule; + and − zoom.

3About

Stephen Wolfram numbered these rules in 1983. looks so random that Mathematica used it to make random numbers. is Pascal's triangle with the odd numbers filled in. Matthew Cook proved that can do any computation a computer can. With a random start, is traffic.