A grid of cells, each alive or dead. At every tick a live cell with two or three live neighbors survives, any other live cell dies, and a dead cell with exactly three live neighbors comes to life. Click or drag on the grid to draw and erase cells, pick a pattern, then press Play. The Rule menu swaps in a variant: B lists the neighbor counts that bring a dead cell to life, S the counts that let a live cell survive.

John Conway devised the rules in 1970; Martin Gardner introduced them to the public in Scientific American. From four simple rules come still lifes, oscillators and "spaceships" such as the glider, which crawls across the grid forever. The Gosper glider gun, the default here, was the first pattern found that grows without bound: it fires a new glider every 30 generations. Variants change only those two lists: HighLife (B36/S23) adds a birth on six neighbors and has a small replicator that copies itself; Seeds (B2/S) kills every cell each tick yet explodes; Day & Night is symmetric between live and dead. Type any rule in B/S form to try your own. With wrap-around on, the grid is a torus, so a glider leaving one edge re-enters at the opposite one.

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