First, the cubes in this particular room are funny; when you enter the room, you will notice them slowly sliding across the floor and into place.
Also, I have played with the cubes in this room for some time, and I am unable to rotate and get cubes to fall down (although I recall in my first play-through a few years ago this happened... there have been several game updates since then).
In general, cubes will follow the same mechanics that hold for the rest of Fez:
- objects inherit the x/y/z-coordinates of the object they are standing on, or placed onto
- if an object is moved so that x/y-coordinates change, the z-coordinate is unchanged until the environment determines the object must be moved into the foreground; even then, coordinates are adjusted so there is as little change as possible
- when rotating, background objects (such as vines or fireplace platforms) may disappear into the foreground, causing your character to fall off them
Please feel free to edit, and add other game mechanics to this list that have been missed.