Langton's Ant
Turn, flip, move: simple rules, surprising structure.
What is this?
A classic cellular automaton where one ant walks over a grid, flipping cell colors as it moves. It looks disordered at first, then produces a repeating highway.
How it works
On one color the ant turns right, on the other it turns left, then flips the cell and moves forward. That tiny rule set creates phases of symmetry, chaos and eventual regular motion.