The architecture of Nirvana allows for "on-the-fly" changes to be made to the game. This includes, but is not limited to, the addition and removal of rooms, items and monsters. Everything in the game is an object and how it interacts with other objects is determined by the code within the objects.

So, just who is responsible for all these objects [rooms, items, monsters]? Why, your friendly neighborhood wizards, of course. Alternatively referred to as Imms [Immortals], Builders, Coders and a plethora of other descriptors, they are responsible for the weapons you wield, the monsters you fight and the rooms you walk around in.