This game takes place far away from any published setting, but the cosmology and deities will roughly be the same as for the standard D&D v 3.5 Ed (Greyhawk) setting. Forgotten Realms deities and races might appear, but assume nothing.
The old order was coming to an end...all the old Ark was threatened with destruction. The mad hermit known as Fraengel the Gristle-Gray came forth from the Throat to weld the Ark anew, out of godfire and stolen stone. He offered escape for those who had no escape. A hundred exiles took up his offer. Only one of them recognized Fraengel as an alienist devoted to the rupturing of the Outer Darkness. One was enough.
His name was Kaol, an outcast Rogue-Librarian of the Nose. When all the exiles were gathered with Fraengel past the Shivering Door for the last rituals to power the Change Engines, Kaol held a mirror to Fraengel's mind, and all beheld his true aim: a new order of slavery and congress with the Old Nameless Ones. Betrayed, Kaol was cast into the teeth of the void. Just before he died, he laid a curse upon his ark.
"Never to rest, never to leave, no home and your only home."
The winds of chaos carried the new Ark to unfamiliar shores. Kaol, the first exile to try to escape the stone ship, was instantly engulfed in heatless flames that rent his soul from his body. The second fared no better. The third placated the ark with promises to return, and she lived to set foot on a new plane, only to die pierced by the poisoned arrows of hostile natives. After that, the other exiles stayed aboard and studied the mysterious Change Engines in earnest.
After months of trial and error and a haphazard race through the planes, the exiles have begun to exercise some control over the engines: at least enough to cause it to shift to a new plane. But now resources run short. The stores of food are running out.
You are one of the original exiles (from the first version of the Ark of Fools MUX), or a defrosted new arrival (souls trapped in the engines of the Ark by the epic-level chaotic magic used to power it. These can be from any world, any plane). As a player character, you are (if you choose), one of those able to cause the Change Engines to shift planes. You may choose any class or race in the Player's Handbook, plus the non-Oriental Adventures classes in the various "Complete" books. Psionics are not allowed.
The Ark is a flat spheroid of gray rock, 400' wide, 220' thick (top to bottom). It floats about 150' from a solid/even surface (grassland or water, for example), but 50' from less dense terrain such as treetops. The landing platform at the "waist" is about 110' from the bottom of the rock. A stone keep grows out of the top, and a ledge of a road spirals down the side.