You will not find a duplicate planet in No Man’s Sky no matter how hard you look, even though there are more planets in No Man’s Sky than there are stars in the Milky Way.
The overwhelming amount of content in No Man’s Sky has been the game’s chief selling point during the years-long hype train prior to release. No Man’s Sky achieves its massive feat of galactic creation by using a programming technique called procedural generation, and it’s a trick that game developers have been using for more than 35 years.
The 1980 computer game Rogue used procedural generation to create unique dungeons every time the player died. The huge, scrolling level in the shooter River Raid, published for the Atari 2600 in 1982, was created via procedural generation. The famous space exploration game Elite, published in 1984, used procedural generation to create eight galaxies, each with 256 planets.
More recently, Minecraft uses procedural generation to create its worlds, Spelunky uses procedural generation to create its deadly platforming levels, and Star Wars Galaxies used procedural generation to create its sprawling planets.
Procedural generation works by using an algorithm that is basically a set of rules for how content is created. If you were to take all the natural laws of the universe and put them together in a single equation, this might be a good analogy for an algorithm that’s used in procedural generation.
These algorithms can be extremely complicated. Think about all the elements that define a single planet in No Man’s Sky. There’s planetary geography, temperature, the placement of plants and animals on those worlds, what the plants and animals look like and how they behave, which elements are present on which planets, where those elements are located, whether there are outposts on the planet, and where those outposts are located.
All of those elements have to be accounted for in No Man’s Sky’s procedural generation algorithm.
This algorithm is the “math” that Sean Murray, a lead programmer on No Man Sky and managing director of Hello Games, is referring to whenever he talks about how the game works under the hood.
Murray in June 2015 granted an interview to IGN in which he explains how math is used to create No Man’s Sky. The interview includes some interesting details on how animals specifically are created for the game.
When you’re playing No Man’s Sky, remember you’re more or less standing on top of a huge mathematical equation. And to think, there was always a kid at school who said math wasn’t important.