In the achievements list, it says that you must cover 75% of the galaxy with your culture (or something to that effect) in order to unlock this achievement. The reason why this confuses me is because you're not really conquering galaxies; you're conquering solar systems. Unless, of course, it really meant to say to cover 75% of the map with your culture; then that would make sense. I'm still confused, because I've already covered 75% of the map with my culture. How would I go about unlocking this achievement?
