No Man’s Sky is an online game. There’s a chance you could encounter another player out there in that virtual universe. This can happen even if you don’t subscribe to PlayStation Plus, because Sony has decided that this game won’t require a membership for those odd chance encounters.
Here’s why things have worked out the way that they have. The odds of running into another actual person while play No Man’s Sky are astronomically low. Because of this, it’s considered a single player experience. So if you do run into anyone, consider it a bonus.
It’s another incentive to go ahead and play No Man’s Sky online, even though you could stay offline the whole time. The first reason to be online is to register discoveries with the universal atlas. As you come across planets and species, you might get to name them. You don’t get to share your insights with others unless you do that, so make sure you’re hooked up to the internet as you play!
Source: Game Informer