The design allows for extraordinary economy in computer processing: the terrain for eighteen quintillion unique planets flows out of only fourteen hundred lines of code. Because all the necessary visual information in the game is described by formulas, nothing needs to be rendered graphically until a player encounters it.

Murray compared the process to a sine curve: one simple equation can define a limitless contour of hills and valleys—with every point on that contour generated independently of every other. “This is a lovely thing,” he said. “It means I don’t need to calculate anything before or after that point.” In the same way, the game continuously identifies a player’s location, and then renders only what is visible. Turn away from a mountain, an antelope, a star system, and it will vanish just as quickly as it appeared. “You can get philosophical about it,” Murray once said. “Does that planet exist before you visit it? Sort of not—until the maths create it.”