It would be interesting to expand the notion of the Subversion Clock to include other aspects of everyday life. A motion sensor could be placed in every room of a house, and assorted mechanisms installed in the walls, doors, windows, cabinets, floors, closets, and miscellaneous nooks and crannies. Anyone entering a room would encounter a perfectly ordinary space. However, whenever the motion sensor in a room detects that nobody is present, various changes start to occur.
Towels might change color, or wallpapers vary in pattern. The woodgrain of the doors might mutate from one visit to the next. The picture on the mantel could change in both content and position. A throw rug may appear on the bedroom floor one day, only to be gone the next time you enter. Window curtains might change to slats, or vice versa.
There are so many possibilities for the inconstant house, so many opportunities for play. And of course the best changes would be the little ones — those that require attention to be noticed. It should not be too obvious that the height of a picture upon a wall has changed, or that a trim little mustache has appeared in that old black and white photo of grandpa during the war. And the pair of old work boots which one day turns to a pair of lady’s shoes should be discretely tucked away in a corner of the library.
Much of the fun would be in designing the house in such a way that the underlying mechanisms remain unseen. There should be no tell-tale strings or wires to trip over or to catch the light. Plumbing fixtures, bookcases and alternating styles of furniture should rotate cleanly around a central hinge, so that the unseen version disappears behind the nearest wall.
And of course, upon entering any room, one should see one of those subversive clocks, always reliably set to a new and unpredictable hour.