This is a prototype of Keith Lam and Joseph Chan's Moving Mario, an installation art piece that wants to draw your attention to the fact that the sense of a character's "movement" attained in old 2D side-scrollers was instead just a scrolling background image. Or, as Lam says:
By phsyicalize (sic) the virtual game, Moving Mario is transferring the movement of virtual character (Mario) to the real world player.
Which is all well and good, but he could just as easily have said "because this looks really great" and I'd have nodded my head in agreement twice as hard.
Moving Mario [via Boing-Boing]
[Moving Mario Flickr set]