i think would be cool to add mini games puzzles etc to the game for example maybe add a chess game challenge to player menu (challenge a player to chess game) with possibility to play different types of games ie: chess, ping pong, tag (with mounts), hide and seek, scavenger hunts etc.. haha the possiblities are endless.
and perhaps a dungeon or map with hidden stuff to find kind of like some of the zelda games have ..might be a good way to make some of the unused maps in game useful.