Toroid

Toroid is Conway's Game of Life, the cellular automaton John Conway published in 1970, on a board you can draw with a finger. Four rules run the whole thing. A living cell with two or three living neighbours stays alive. One with fewer dies of loneliness, one with more dies of crowding. An empty square with exactly three living neighbours comes alive. Every cell updates at once, and that is the entire game — there is no score, no goal and no opponent, only what your starting pattern turns into. The board wraps at every edge, which is where the name comes from: the grid is the surface of a torus, so a glider that walks off the right side reappears on the left instead of falling off the world. WHAT YOU CAN DO - Drag a finger across the grid to draw cells, and drag back over them to erase - Play, pause, or advance exactly one generation at a time - Set the speed anywhere from one generation a second to sixty - Drop in six known figures: the glider, the blinker, the toad, the pulsar, the R-pentomino, and Gosper's glider gun, which fires a new glider every thirty generations forever - Fill the board at random and watch it settle into still lifes and oscillators - Watch the generation count and the living population as it runs Try the R-pentomino. Five cells, and it takes more than a thousand generations to stop changing. Toroid has no accounts, no network access, no analytics and no advertising. It never collects anything, because it has nothing to collect it with. The whole game is arithmetic running on your device.