When the creators of No Man's Sky revealed that every facet of their massive space exploration game was procedurally generated, they weren't kidding. To that end, cofounder of Hello Games Sean Murray revealed that the total number of generated planets makes visiting them all individually impossible -- unless you have five billion years to spare.
Murray told IGN that the team had originally been using a 32-bit number to help code for every planet in the in-game universe. This created a total that would take around 5,000 years to see in its entirety, but unhappy with this level of unfathomable detail -- and to prove wrong the naysayers on their forums claiming technology limitations make it impossible -- the decision was made to step up to 64-bit.
As a result, No Man's Sky will feature 18,446,744,073,709,551,616 worlds. That's 18 quintillion, if you were counting. Visiting each at the blistering rate of one per second would take five billion years (with no toilet breaks) and quite a lot of rocket fuel. You would also need to secure alternate accommodation and power sources because our Sun plans on running out of its own fuel in around 4.6 billion years.
This hasn't put the team at Hello Games off attempting to catalogue every planet in their virtual universe, however they have had to enlist an army of bots instead of human testers to go out and take photos from the surface of each one. Lucky bots.