Umbran said:
1) There is no "must" here. There is no reason why that extra dimension cannot be spacial, rather than temporal.
I think what he was getting at was that after you have defined your physical dimensions,
however many you have, you're still going to have at least one more than defines the object's transition through time - so for a 4D physical object, that would be a 5th dimension, and for a 15D object, it would be a 16th.
Umbran said:
2) And, even if it is temporal, that 5th need not represent a "change" in anything. You have three physical dimensions in your body. The 3rd one of those does not represent a change in either of the first two.
Without at least a potential for change, dimensionality is meaningless. I could say that I have a 4th dimension to my physical existance called "feidth", and maybe even come up with decent math for it

, but unless something
actually moves along a change scale of feidth like they do width, it is complete bullpocky.
Here is a list of 9 dimensions that have occurred to me for use in an RPG, none of which require extensive math and study for players

:
1. Length
2. Width
3. Height
4. Transformation Through Time
5. 3D/4D Abridgement Dimension
The non-directional "direction" that magical transportation uses. Kinda like the sci-fi standard on how wormholes work - accessing an extra dimension that allows one to shortcut across the curves and folds of spacetime. Generally in games, the Astral Plane is substituted, or travel across this dimension is made instant, because the senses of normal beings rely on mechanics that wouldn't work right in a wormhole, and it would either be very boring, deadly, or possibly both. (One could go another route, though, and get extremely WEIRD, in a literary sense (strange tenses, descriptions of things occurring that are physically impossible to the extent of them seeming almost nonsensical), in describing movements and actions through this dimension - depends on how much you think your players would enjoy and or understand it.)
6. Instant, but Scaled, Transformation Through Magic
Basically, this one is assigning a magic value to points in spacetime that changes in a linear manner independent of the previous 4 dimensions listed. I think this would work, in game terms, like a systems of continuously moving "power points" that would play light havoc with attempts to use magic. You would probably want to make magic-users make a Spellcraft check or some such to determine where one currently is, with difficulty increasing based their movement through the first four dimensions since they last encountered one. Also, this would involve a random check on the part of the GM to determine if they've
inadvertantly interacted with one. If players ask how it really works - metagaming - tell them to do the same math that their character does to figure it out, and they'll see.
7. Spirit Qualitative Dimension
A dimension in which the spirits of every being in existance reside - in one physical and temporal point, but transforming along the scale of the differences between those beings. (How many angels CAN fit on the head of a needle?

) Beings transform through this dimension through the quality of their spiritual existance - we'll call this mechanic "alignment".
8. Spirit Quantitative Dimension
A measure of the allocated "strength" of a person's spiritual presence at a specific alignment value, transformed through time. Alignment based creatures (demons, angels) exist without transformation through the 7th dimension, and therefore have a continual increase in the 8th, and can, in fact, willfully force accelerated increase from time to time in order to achieve superior magical effects. (See below)
(In a similar fashion to the way increased movement through space decreases movement through time, there is a relationship between the 6th, 7th, and 8th dimensions: Increases in movement through the state of spiritual quality cause changes in movement through the other two. A good in-game mechanical example of this would be the Cleric of a dark god who wishes to perform a powerful ritual might spend the weeks before doing ritual clensings and going about performing minor good deeds, or the Cleric of a good god might humble and belittle himself and perform a series of sacrifices of innocent creatures, so that the sudden dramatic transition between these preparation acts and the actual ritual through the 7th and 8th dimensions has the effect of causing a large-gravity-well-like effect in the 6th, pulling a large, helpful "power point" to them at the time of the ritual.)
9. Attaway
Any game that deals with dimensional mechanics needs a "Attaway" dimension - a dimension through which the characters are transported to another place, plane, or time, in a way that is described to them as their minds screaming that this isn't a valid direction to be transported in. Some sort of temporary or permanent sanity loss is in order.
![Devious :] :]](http://www.enworld.org/forum/images/smilies/devious.png)