There are over 18 quintillion possible planets in No Man’s Sky, according to Hello Games managing director Sean Murray.
That exact number is 18,446,744,073,709,551,616.
“Even if a planet is discovered every second, it’ll take 585 billion years to find them all,” Murray said on the PlayStation Blog.
“The cool thing is that every planet has a single number, a random seed, that defines everything about that planet. A single random seed generates every blade of grass, tree, flower, creature. So as the developer I can note down the planet seed, and then just go back there any time I want. We demoed this at Gamescom, just jumping round the universe to different planets. There are no load times, because nothing needs to load, as the planets are entirely computer-generated.”
There is a “core game” to No Man’s Sky, including “trading, combat, weapons, ships,” and such, but the “quiet moments of discovery” are what the game is all about, according to Murray.
Recounting one of his recent play tests, Murray said, “I neared the surface of a planet and suddenly it started to rain. As I was touching down I scared some deer who broke through the woods, dodging in and out of trees. Now this was jaw-dropping to me, because I’ve never seen any of these systems before, but also it felt like this was a real place I’d discovered. No one had been there before, and I didn’t know whether to shout excitedly, or just keep it to myself.”
http://gematsu.com/2014/08/mans-sky-18-quintillion-planets#vZVh1eK6LGYt4oSL.99