I have been wondering about this for ages...I always thought that fighting games that made you fight on something other than a flat plane would be an interesting concept, since you could do things like escape from corner traps or juggle enemies off stage pieces to create long combos. But I've only seen it used in about two games (Smash Brothers and Savage Reign.) 3D games have been doing it for ages but I wonder why it hasn't caught on with 2D fighters (bugs? Turtling problems?)