Once you've won Endless Space somehow, can you still earn Steam achievements? Or do you have to go back to a saved game before you won, and earn those achievements before your victory?
Having tested this, I can say that yes, you can earn Steam achievements after victory. (I earned "have 1000 science in one system" after finishing a score victory.) You can even get the "Victory via X" conditions after winning; you can win economic, diplomatic, expansion, domination, wonder, and science victories in the same game; the game won't show a victory screen, but you'll get the achievement.