The features are nice, as I will only be playing in sandbox mode. There is no way to claim the lands of a destroyed clan to start a new kingdom. You have to be a vassal to another kingdom, and HOPE that they vote to let you keep the spoils of your hard earned fighting. The only way to get your own kingdom in the single player campaign is to grind away, build your clan rank, and take a castle on your own, which is impossible unless you weaken a faction, all by yourself, so they can't send an army after you.