I guess I should of said mt infinity from digimon world 1.
I don't know much, if anything, about Digimon World as I did not have a playstation as a kid and simply couldn't get into it later. Rumble Arena and Digital Card Battle were more my thing. Which brings me to another suggestion:
How about the Deep Void from Rumble Arena? It represents no specific area from the digital world but instead sybolises its outer reaches, where everything is pure data and things like "land" and "sky" do not exist.
For the purpose of the fight, lost and floating code has formed a thin wireframe that, despite its massive gaps, still somehow supports the combatants' weight. Or rather, the concept thereof, since were there no floor they would simply float in the absence of gravity that fills this place.
Yes, this entire stage is a bare bones representation of what the fighters will it to be and this means that, wherever they go, it will follow. Their feet will always be supported and they will never be able to walk out of bounds.
The stage is infinitely large, yet always enclosed within two rings of digicode text that may or may not contain secret messages for fans to decipher. These will expand and contract so as to always be at the screen's edge, regardless of how far apart the fighters may be, but do not think they can expand forever, oh no! A mysterious force pulls players towards the center of the screen, the degree to which it does so entirely proportional to their seperation, ending only when they are a mere two stagebuilder blocks apart. Because of this, players cannot simply run away and expect to remain uncaught, yet should they run together, they can run forever.
Now, this does of course make horizontal KOs harder than normal, quite substantially so infact, but it does not make them impossible. You see, the camera can only move so fast. Should they be launched hard enough to pass through, over, under or between the rings of code, they will die instantly, without ever seeing the magnifier bubble. This can actually act as a boost to certain long range and hard hitting projectiles.
In short, this stage represents the place between worlds where fighters from between the two due it out. It is entirely flat and has no bottom blast zone, yet it is not walk-off either. It is not, however, walled on 3 sides and does allow for horizontal KOs, though it obviously favours the vertical sort. Despite this favouritism, however, it has a extra hig