“Isn’t it strange that though this is the Foundation of the maze (possibly the lowest room) that one still has to go “down” to get to Room 29! I mean, is there an elevator down there or something? ;)”

Sometimes you can tell what the connection is for an unlabelled door, as in this case, because there is only one: Rooms 6, 11, 29, and 38 lead to Room 40, but only the door from Room 29 is a one-way connection. In other rooms with multiple unlabelled doors, you don’t necessarily know which door comes from which room. (See Room 22 or Room 11, for example.)

(White Raven has helpfully listed the connections just above each Solution Summary on each room page, with the unlabelled (one-way) doors greyed out and unlinked to show that you can’t get there from here.)

Most of the time, there is no obvious connection between how the connecting doors in rooms appear (open vs closed, arch vs standard door, etc). For example, compare the doors from room 26 to 36, 4 to 15, and many, many others.

There are a few exceptions, in which the doors are obviously connected in some way, such as the slide from 41 to 38, the tunnel from 27 to 9 (or from 9 to 27, depending on the theory you ascribe to) and possibly the ladder from 41 to 35. Maybe a few more I’m not thinking of?

You have discovered one of my favourite aspects of Maze, which is that you can spend a lot of time imagining what exists between the doors. Sometimes we get a sense, as in when the visitors pass “down a long flight of stairs, through some sort of pantry” as they leave Room 3, but usually it is left up to the reader’s imagination.

Presumably there is a bathroom or two somewhere along the way… ;-)