Back Dimension is the given name to areas corrupted by Analogman's soul over the Digial World. They are consistently portrayed as having Mt. Infinity's same appearance, though the layout is convoluted, almost maze-like. At the end of each Back Dimension, a possessed Digimon forced to evolve into Machinedramon awaits. If the Digimon were to be defeated in battle, Back Dimension would fade from that location, albeit temporarily.
Back Dimension is only reachable after beating the game for the first time. Back Dimension are places corrupted by Analogman's presence, and are the only locations he is allowed to exist. As for the game, the only places corrupted by Back Dimension are the Ice Sanctuary on Freezeland, Grey Lord's Mansion at the Overdell and Ogre's Fortress at Great Canyon. Only one of the locations will be taken over at a time each 22 in-game days after the last Back Dimension faded; the player will be prevented from entering the non-corrupted area until he or she beats the Machinedramon at the end of that particular Back Dimension. Analogman's materialized soul may also be seen inside each open Back Dimension.
It is implied that the final battle with A, as well as most of the game's epilogue occurs on a Back Dimension opened at Infinity Tower. The possessed Digimon was an unsuspecting VenomMyotismon, but rather than transmogrifying into a Machinedramon, it retained most of his usual appearance, albeit with severe facial disfigurement. This particular Back Dimension was cast off by a security system after A was beaten.
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