Cuorebrave, come off your high horses, please.
The question was to the effect of what would be the scope the game would need to have so the completionist kind of gamer would find it too big to complete. In my case, 1000 hours, give or take a few hundreds. It means that if the game has about 100 hours of very meaningful content, plus an extra 400 that I can do but that will be of limited significance or even just grind/rote exploration, I will complete it and visit every star, every planet, every moon, every asteroid, every speck of dust.
As to the player-created universe, I might also play them as well. But when talking strictly about the company-issued campaign/storyline/universe, it will have to be freaking big, if Stardock wants to make it so that I give up before reaching the real borders, so I never get to see them and so they can improve the impression of verisimilitude.
When I test software, I do (what we call) TUF. Test Until Failure. In sci-fi, you'd say I like to boldly go where no geek has gone before. And if I reach the borders of the universe, three things will happen: 1- I will feel slightly disappointed that I'm not REALLY in a spaceship without real boundaries beyond what my fuel tank can yield, 2- I will explore everything within the confines of the borders, 3- I will try to breach the borders, even if it is to discover a BSOD/Error message that no one has found before. Or maybe I find a hidden wormhole that will bring me to a very small area that no one has found before and that has a single planet with a single monolith on it that, once the Universal Translator has been used on it, I gleefully learn that it says: "You're one obstinate SOB. You now have bragging rights. -Stardock"