This is an area that is pretty open. There have been only a few other

dimensions mentioned so far, over the course of the game. But first some

terms need to be defined:

Alternate Universe: The most "common" type, a universe like our own except

certain events happened differently. Potentially infinite (any event has

several outcomes) they are effectively limited by certain obscure laws of

temporal physics. What it boils down to is that timelines with minute

changes do not have enough "momentum" to continue and reunite with their

main timeline almost instantly, existing so close on a quantum level as to

indistinguishable. It has been theorized that being displaying unsually

positive or negative "luck" may somehow instinctively jump around these

minor alternates but that has never been confirmed. An example Alternate is

the home dimension of Protector and his order, the Quantum Knights. Its

seems to be an Alternate Earth inhabited by a humanlike race that follows a

belief structure that says evil is an actual force that must be combatted.

Variant Universe: Much more distinct than a Alternate, A Variant "branched

off" from the some unknowable time in the past, perhaps right at the Big

Bang. Totally distinct, these Universes may have different physical laws. The

line between Alternate and Variant can be hazy. A good example is a Universe

encountered by the Defenders where superhuman powers not only did not

exist. but there existence wasn't supported by the laws of that Universe.

History of the Earth was mostly the same, however except there was no

Tyranthrax invasion.

Outer Plane/Realm: These are the "magical" planes of existence. The Astral

plane, Tartarus, Fairy and other realms thought inhabited by magical and

unbelievably technically advanced beings. There can't be a blanket definition

for these realm as they are as diverse as there inhabitants. Some are actual

"places" such as the Astral Plane and can be observed scientifically to an

extent other are abstract like the Dream Zone, existing the universal

unconscious of every being that dreams.