I think this game deserves a really cool social mechanics sistem, like in the Fable games, where you can have relations with players and npcs, get feedback on your actions, reputation, love or hate from the citizens, animations for living a life in this amazing world, including housing activities, life needs animations like bathing, dining in your living room, reading books, hability to write books and letters that could be sold or stored in a library or shop that could share your creations with the whole comminity.
Animations for interacting with npcs and players, instrument system that allows players to add songs tuned for the instrument or voice.
Deep pet & familiar system.
Social activities & jobs, that are done inside the city, like bards, performers, manage or work in the inn/tavern/shop with its own mechanics or minigames.