Not much is know of this strange and alien entity as it do not collect followers as most gods do, it have no real priesthood or scripture. The only source of information is what can be surmised from the few successes of communication with it and some clues from its interactions with the different worlds where it has precense.
It is concluded that it was a lower Godling or assistant to a god of conflict and challanges. Perhaps it grew overconfident, perhaps it was framed but it fled or was exiled. As with many other beings that had a need of hiding from mightier powers it travelled to the outmarches of reality, where the edges folds and wrinkles hiding pockets of worlds allowing for experiments and creations not allowed where more responsible powers oversee things.
In the Outmarch there exits half-finished world that never was properly put together before abandoned as well as paradisiacal hideouts, heavily defended and/or well hidden. But most worlds are struggling creations of Godlings lacking the strength or talent to create a fully functional world.
These world struggles continuously sapping the strength of the Godling in question until it perish or abandon its hopless project or, in the best case, carefully balancing on the edge, treading water just keeping its breathing tubes above the surface of oblivion.
Here the Dungeon’God wandered for a long time, sustained by some power it had stolen from the old master and replenished by stealthy conflict stirring at worlds lacking in defences to keep it out.
And it was during one of those forays that Dungeon’God got its bright idea. There was those who tried to make an existence by trading between the different worlds, but most perished sooner or later, the profit margins was small and there where paranoid half-mad entities everywhere. Dungeon’God had to come up with a way to trade which both was safe and provided it with sustenance. As it was not a Godling of trade, the trade in itself was useless as a source of power, at the most some power could be drawn upon if it was a challenging trade with dangers of conflict and difficulties.
Instead Dungeon’God devised a plan most cunning, by using resources plundered from a dying world and enlist the helpless souls there. By turning its body into a incomplete and limited world and connect it to worlds in need, luring its inhabitants to enter and find much needed resources. The supplies where guarded but not impossible to defeat, but increasingly difficult, always a challange, never impossible, Dungeon’God got nourishment and power to connect more worlds, transferring goods from one to be plundered by another, always strengthening the Dungeon’God.
The creators or godling maintainers of these world was often served with fait accompli, as the cost of dislodging the Dungeon’God would be to great (a parameter well researched by Dungeon’God) negotiation usually lead to an mutual profitable agreement, perhaps not for those who enters the Dungeon, but for the world as whole.