In addition to planar cosmology, there exist "alternate" realities, variously referred to as alternate worlds/alternate primes or dimensions.
"Cloud World" from Q1 "Queen of the Demonweb Pits" (1980). Illustration by Erol Otus.
There is a "prison" dimension mentioned in B3 "Palace of the Silver Princess" (1981). The "Dimension of Nightmares" and "Dimensional Vortex" (the void between all dimensions) are mentioned in X5 "Temple of Death" (1983).
Beyond the Multiverse:
Unsuspected by all but the most powerful magic-users (M26+), beyond the multiverse are alternative realities, called "dimensions." It is guessed that other dimensions coexist in the same space as the multiverse, yet cannot be detected by mortal perceptions. Even Immortals, with their heightened perceptions, may have limited powers in alternative dimensions. One such dimension is the Nightmare Dimension, which is inhabited by creatures that haunt the dreams of mortal and Immortal alike.
Past all planes and dimensions lies a mysterious barrier, called the Dimensional Vortex, home to horrific monsters called "vortex creatures." Here, even the Immortals fear to tread.
Rules Cyclopedia (1991)
Frank Mentzer describes an alternate concept of dimensions in the Immortals Set (1986), in which five dimensions govern each plane of existence. In this construct, the Dimension of Nightmares represents the fifth dimension.
While I appreciate Mentzer's cosmology, it departs significantly from AD&D 1e cosmology. I favour a B/X cosmology distinct from BECMI, emphasizing the adventuring opportunities in "alternate primes" and/or dimensions.
Do the rules explain what distinguishes a "multiverse" from an "alternative reality?" Is the multiverse intended to be an entirely separate set of planes from the AD&D "Outer/Upper/Lower Planes" cosmology?
ReplyDeleteGood question - it's dealt with a bit separately in D&D 1e and BECMI.
DeleteIn AD&D 1e the prime plane is a universe, and so alternate primes/realities represent alternate universes - the span of which comprise the multiverse.
BECMI regards the prime plus its various planes as a multiverse, and alternate primes as a "polyverse".
I prefer the AD&D 1e interpretation, although the BECMI construct is important for its cosmology.