So, I've created my Sim and I wanted to build everything myself, but I didn't know for what these rooms were for.
So I decided to re-run the game and choose for second option, which stated it would use traditional set-up for Sim's castle. It looked wonderful, but I wasn't able to switch to Live Mode, where you can actually live and play.
I haven't changed anything. It's straight-forward. I just selected "Traditional set-up", created my Sim and then when I saw my castle, it was already greyed out.
Anybody an idea?