As gamers we understand the limits of game worlds. We know that those mountains are impassable, that your character can't swim or that your PC couldn't possibly render a city any larger. It doesn't bother us as long as the confines of that world keep us entertained. But, at a certain point the mini map is full, the game feels completed, and you turn off your console.
But what if that world could never be fully explored? What if somewhere in the corner of a galaxy, on the edge of the universe, there could be an alien creature that looks exactly like Hillary Clinton. Sure, it's unlikely, but when a universe is created using math with seemingly random variables, and it's populated by creatures that were conjured from the same, unpredictable system - who's to say that a pack of wild Hillary Clintons aren't foraging somewhere in the dank recesses of an alien jungle?
It's that idea that makes No Man's Sky such an exciting prospect. Not that the former Secretary of State is a four legged herbivore, but that there is always something new and wonderful over the next horizon. And that you could be the first person to see it.