I would love to see the White Walkers as a Barbarian faction. Like, maybe the white walkers spawn every time a unit dies and kind of attack passively at first, and maybe there's a flag that enables them to walk further and further south until they attack all of Westeros. You could also have Wildlings as Barbarian units that can somehow be accumulated into your army if you kill a certain unit or something. Maybe my brain is still stuck in old school Civilization II and its functionality, but I would hope there's a way to do that in Civ V. I love Civilization and I love Game of Thrones