Universal constants, are they different from our universe? Gravity seems pretty close.
Gravity = 9.8 m/s^2
Speed of Light = 299,792,458 m/s
The Cleft - or at least the Middle Realm of the Cleft - is a sphere. It is not necessarily a solid sphere, like a normal planet, but it looks like one from the outside. The radius of the Cleft is approximately 1,600 miles. As the Immortals modify the Cleft, this figure is bound to gradually grow.
Planetary bodies outside the main surface of the Cleft (such as the moon, Zebes), retain the planetary properties they had in their original universes. Zebes is still a solid planet with a molten core.
Due to the Cleft being hollow, it is not as massive as a planet normally would be. Yet, it still has gravity equivilant to an Earth-sized planet. Carsanquay has a machine in the center of the Cleft that generates the missing gravity and compensates for other necessary physical forces.
The Cleft has three distinct realms:
The Upper Realm, containing the Mana Holyland and most Immortals.
The Middle Realm, containing most of everything.
The Underworld, home of the dead and also Dreadite and his posse.
Where did this place come from? I think MTS's origin story and the current story (shown with the 'story' command on the MUD) is correct except for that sword reference.
Crashing. Banging. All around portals opened up into an unseen void, spewing forth chunks of land and various gigantic pieces of matter. As if subject to a fluctuating force, they stop and start, plummeting into some semblance of order. Various gravities and atmospheric pressures boggle together and meld. With a static charge, an acceptable level of friction buzzes into existance. And as a din and a racket clatter across, a new dimension fizzles into life.
From a rift in the newborn sky, a mountain steadily drops and makes an enormous splash in the sea below, sending flames and sparks crashing outwards. It shifts over and collides with another landmass, anchoring it in place. Phasing into reality, a fully-developed castle, complete with bits of swarms of bats, materializes elsewhere. Freshwater and saltwater, with all their variations of salinity, swirl together in a menagerie of seas. Meanwhile, in other already established dimensions, towns and villages disappear into clefts of blackness. Befuddled townspeople wonder what could possibly be going on as pieces of the world they know slip out of their reality.
A certain divine guilty party, wielding a dimension-disrupting sword, shuffles his feet back and forth for a few moments before mumbling, "Oops."
Meawhile, in the ever-filling cleft between dimensions, a new world is forming out of parts of the old ones. Landmarks from various realities and universes flood into the landscape. Noticing an excellent opportunity to certify their power, would-be gods enter the realm, establishing it as their own to rule and develop. Organizing the cacophony into a respectable microcosm, the immortals create order through clever schematization and divine prowess. But being immortals, these pioneers desired more from their makeshift dimension. Prodding at a wormhole floating above the city of Truce, one of them creates a static gateway from reality to the cleft of dimensions, allowing people to enter as they please. With help from new adventurers entering the cleft, a new dimension achieves greatness.
Stuff Falling In
Consequent to the Cleft only existing due to anomalous physics, the dimensional fabric of the Cleft is fragile. Frequently, rips open within the dimensional fabric. It is through these rips that pieces of other dimensions slip into the Cleft. This is generally a bad thing for the source dimensions, but this process is the source of all matter in the Cleft.
The Immortals are responsible for maintaining the integrity of the Cleft by figuring out to do with incoming pieces of other dimensions. Some are incorporated into the Middle Realm, others are shoved aside. Additionally, the Immortals - especially Carsanquay - are responsible for repairing dimensional rips before they grow too large.
It would be catastrophic if a black hole, supernova, or other high-energy cosmic phenomenon spilled through a dimensional tear.
It would be possible to escape the Cleft through a dimensional tear, but it would require a powerful spacecraft. Although people are able to enter the Cleft, it is believed that escaping would most likely kill any traveler due to the sudden change in fundamental physical laws uponing entering a new dimension. There is also the possibility of creating a temporal paradox dependent on the dimension to which the traveler escaped.