Re: Building with Platforms (multiple rooms)
Well, in your image, it's impossible for the door to be on the "ground" of the larger room because if it was, it would be blocked by the raised part of the smaller room.
Although I think I see what you're saying. The larger room is sunken, and the smaller room is the normal height?
You can color the side of the platform using platform trims, but it won't look the same. There aren't as many options.
You can put wallpaper on half-walls and you can put half-walls on raised platforms but not sunken platforms.
That does sound like something that needs to be changed. Add the ability to put all the new half-walls on the sides of sunken platforms same as raised platforms. Or at least be able to use normal wallpapers and such on the sides of sunken platforms.
(Thinking...)
I suppose the only way around it would be to create platforms all around the house, like on the porch, and the interior flat on the ground. That way it would "appear" to be sunken. But not. Then, when you create the smaller room, you'd use a "raised" platform and you could use normal walls around the outside of the room and wallpaper it normally.
You'd still have to use a set of stairs to get into the small room though...