Quoted from TractorDoc:Cameras strategically placed in/around the playfield is an idea -- this way you can record/review a good ball or game similar to video games.
I remember hearing some buzz a year or two ago that JJP was playing with the idea of a subterranean playfield, like black hole, only visible on the LCD display via cameras while the ball was down there. Don’t know if anything ever materialized out of that design. Sounds like it would be difficult to play.