A game inspired by the Borrowers, Arrietty and the Littles?

The new trailer for Studio Ghibli's Arrietty has me thinking about the potential for a game inspired by that general premise: Hidden elflike people hide in our walls. Here are a couple quick ideas:

Your story is set inside the home in which you play the game.
Any pets in the home are hazards for your characters.
Character art is drawn at actual size. (About an inch or so.)

So what's the compelling situation? What is the common thread each time you play the game? What is different each time you play? Hm!
Daniel Solis
Art Director by Day. Game Designer by Night.