I would love a story of Tyrion visiting the Reach and giving his opinion to his father. Or that he remains under guardianship so that he can be a spy.
A lighthouse is missing in the port in Assassin's Creed they had one.
Do the Prussians still think of Westerosi as savages? I think you could include some dialogue that might suggest that in a more subtle way. I doubt they’d be overt in their distain, but it would be cool to see a smart character catch onto it.
Start creating ships with incredible Greek fire, as well as defenses in cities using the same material to destroy battering rams or any type of attack on city gates or castles.
How about making an attempt on Wilhelm's wedding, but his bride will die "she just doesn't seem like the right match for him."I want the action of a real Game of Thrones.