Hey, thanks for playing :)
So, RC means "rez-de-chaussée" in french (It's the ground floor)
For the "dream sequence" it was intentionnal that there was no wall, to confuse people like "are we dreaming or is it real life ?" that's why you can "go to sleep" during this sequence.
Also, spoiler, there's no basement, the door is closed .. but will be open in the future update ;)