Gosper

In 1970, a mathematician named John Conway wrote three rules on a board: a cell with fewer than two neighbours dies of loneliness, one with more than three dies of crowding, and in an empty space with exactly three neighbours, a new cell is born. That is all. There are no other rules. And out of those three sentences come ships that cross the screen, guns that fire forever, clocks that beat in exact time, and structures that copy themselves. Nobody programmed them: they were in the rules all along. Gosper is a place to watch it happen. WHAT YOU CAN DO • Draw with your finger and press play. Zoom in, zoom out, change the speed, step one generation at a time. • Drop machines from the library: forty historical patterns, each with who discovered it, in what year, and what it does. Nothing invented — every one is checked by a test that verifies its period. • Change the rules. Besides Conway's original there are seven more: HighLife, which replicates itself; Seeds, which explodes; Day & Night, which is symmetric. • Save your universes and come back to them. • Share them with the community, and bring home other people's. • Duel against the machine. Two gardens side by side: you throw machines into its garden, it throws them into yours, and you win by leaving its garden with less than a quarter standing. Build your own deck from the library, from patterns you cut out of your own universe, or from the community. WHY IT IS FAST The engine is written in C++ and computes in blocks of bits, not cell by cell. A universe of a million cells runs at sixty frames per second on an iPhone. Cost depends on what is happening, not on the size of the world: a huge, nearly empty universe costs nothing. NO ADS, NO SUBSCRIPTION No advertising, no analytics, no user profiling. Gosper Pro is a single optional purchase that adds five more themes, giant universes and unlimited saves. Nothing that is free gets cut back to push you into paying. EIGHT THEMES Neon on black, ink on paper, pure black and white, mossy greens, magma, ocean, the amber phosphor of an old monitor, and pastels. The name is for Bill Gosper, who in 1970 built the first glider gun and won the fifty dollars Conway offered to anyone who could prove such a thing could grow forever. That gun is still firing inside this app.