It would be cool if we could by areas that attach onto our castles. Like for instance a pool, or a cave system, or a mountain range that blends into the scenery of our current house.
I think it would also be cool to like add like secret rooms and tunnals to a castles that you could add to the free castle that you could get once you reach level 15. You could even casts some spells that could costoms your caslte to be one of a kind or you could buy a already costom castle.
