The Depths to Which I Sink is a soft of software toy that requires old-school 3D glasses, the kind with tinted plastic panes. The basic dynamic is the same on each level; you control a dot, which moves in the X and Y dimensions with the arrow keys, but moves at a constant speed in the Z dimension downward to the "edge" of the play space, and then back upward.
Different levels (there are three in the demo) offer different challenges; in one, you try to move your dot through floating rings, in another to "break" floating window panes, and in another, you try to move through tubes. There is not, however, any scoring, so it's more along the lines of a play activity than a classic game.
The Depths to Which I Sink is a 2011 Indiecade finalist.