> It's not possible to introduce inside doors or walls here, for example.

I don't understand. Inside doors? And this could be possible by transforming already built walls.

> And maybe I want to have one side completely closed or open?

I really don't see the sense in this. The only advantage is transportation. On the other hand we could just design the towers with wider doors.

> And what about drawbridges?

That's a transformation of a tower, I mentioned that ;)

> Door(s)

Again, what doors?

> Ladder (to get one level higher)
> Castle elevator

Well, no problem with that.

> Production specialisation? (only because you mentioned it, I don't quite understand that particular idea)

You create this one, construct e.g. a forge in front of it and then the forge is boosted. Just because production in a melee is so unpopular (to much time, to less effect).

> For extending your castle, you *should* have to go outside, that's a tactical issue.

Well, it's a tactical issue which totally destroyed the setting that you build your castle while fighting the enemy.

> And the nose thing isn't really something that I feel we should encourage.

It's already possible to make this (and it's done) in CR, by using 2 chunks of loam. This will just make it easier.