Lol saying that Age of Decadence is "edge". If anything the game was very tame for something inspired in Classic Antiquity.
Edge is the matter of MC's story, rather than a quality of the setting itself. As someone pointed out recently, ME1's plot, as seen by some npcs, can be classified as sci-fi horror. But from the players perspective it is not, because they have a prestigious and rewarding journey.
So you could likely have a heroic pleasant story set in antiquity, that would stay true to antiquity. Same goes for most settings, fictional or not.