"It is a shot using real in-game assets. The guy on the cover is actually the "player character" who we use most often when we're playing the game right now. Obviously he has been posed by hand for purposes of the cover, but there is no graphics magic or sleight-of-hand going on. It is not a high-poly render or something that we're only using for cutscenes or anything like that. That is how his armor will look when you play the game. The same for the horse, his face, and the castle in the background - all in-game assets that are rendered in real time by our engine."
ezt egy bethesda developer mondta az rpgcodex fórumán (forrás).