• General Notes
• Alignment, or Lack Thereof
• Specific Planes

General Notes

Some of this has already been covered in other chapters; in a campaign setting about the multiverse of planes, it's hard to discuss a conversion without mentioning the planes now and again! See the chapters on Magic and Characters for conversion advice specific to those topics.

When dealing with the physical effects of planes, rather than try to convert AD&D damage dice into something appropriate for GURPS, try to find something in one of the GURPS books that deals with the effect in question. Falling, suffocation, fire, poison: many of these hazards are dealt with in different GURPS books. The Compendium II has a chapter on hazardous environments. (Some of that is reprinted from GURPS Space. Indeed, perversely, a few parts of GURPS Space are in fact applicable to parts of the Planescape universe; consider the Plane of Vacuum!)

If all else fails, and you just must convert damage into GURPS terms, keep in mind that (depending on the optional rules you are using), characters tend to only have 10-16 hit points in GURPS, whereas they can have a whole lot more at even moderate levels in AD&D. If something is listed as doing 4d6 of damage, it's probably not intended to kill reasonably experienced AD&D characters... but it will probably render most GURPS characters unconscious. GURPS characters can also less afford to lose "a hit point here, a hit point there" than can all but the lowest level AD&D characters. On the flip side of the coin, everything in GURPS is deadlier than in AD&D. The swing of a sword by a strong warrior stands a fair chance of knocking out an unarmored GURPS character, even an experienced one. This is not the case at all but the lowest levels in AD&D. So, it may be appropriate for various deadly planar features to be just that much more deadly in GURPS.... In the end, this is left up to the judgement of the GM. I may list some advice in the section on Specific Planes below.

One final suggestion: consider using the DR of armor (especially magic armor) to reduce damage to character. Try to find a comparable situation in a GURPS book for guidelines. Armor with respectable DR is a good way to have a hope of surviving deadly combat in GURPS. It may be useful against certain other hazards as well. Use logic and good sense.

Alignment, or Lack Thereof

I've already ranted that alignment is a bad idea and unnecessary even for Planescape in the alignment discussion in the Characters chapter and in my page on Why Planescape Doesn't Need Alignment. To be honest, I really don't want to talk about it any more.... I don't like alignment, and prefer Planescape without it. The GURPS mechanics don't have alignment, so I see no reason to tack it on. The rest of this discussion assumes that the simple AD&D alignment mechanic, either for characters or for planes, simply doesn't exist. If you want to, feel free. I try to emphasize that Planescape as a setting stands on its own without the alignment mechanic by giving each plane a soundbyte other than their standard "alignment" soundbyte (e.g. "Arborea, the Plane of Chaotic Good"), which I find unsatisfying. (See below for more details.)

In many cases, the TSR materials about Planescape describe a plane's limitations or effects on characters of certain alignments. In these cases, what the GM should do is take on the role of the plane, and judge the character; if, in the plane's view, the character is "evil" or otherwise inimical to the plane's nature, then impose the limitations or effects. (It may sound like I'm asking the GM to be terribly arbitrary. However, as I mentioned in my alignment rant, this is really no different than what the GM does when using alignments and putting any sort of thought into the matter. A good GM who does use alignments won't let a player get away with just writing an alignment on his character sheet. The GM will judge the character's thoughts and actions to determine if the character has truly remained within his professed alignment. I figure, once you're doing that, why bother with alignments at all?)

Specific Planes

Obviously, I haven't written something about all of these planes yet. I may never write anything about some of them; either I haven't thought in detail about that plane, or I consider that plane one whose mechanics conversions are best handled by GM improvisation and the general advice I've already given.

• Outer Planes
  • Planes of Chaos
  • Planes of Law
  • Planes of Conflict
  • The Outlands
  • Sigil
• Inner Planes
• The Astral
• The Ethereal

Outer Planes

One thing I do intend to do for all of the outer planes is to give a "soundbyte" for that plane, so that you can call the plane the "Plane of Something", where Something is something other than an alignment. This is to fit in with my assertion that Planescape has a disctinctive character, and that the planes have meaning, even if you aren't using any sort of alignment. I believe that my short names are more fitting than the gratuitous alignment labels, and have more to do with really what is the greatest overriding nature of the plane. Naturally, however, a few words can't do any plane justice, be them alignment labels or my labels, so my labels really only scratch the surface of what each plane is all about.

Planes of Chaos

All the planes on the right side of the Great Ring are philosophically bent towards that vast and nebulous characteristic which might be called chaos, though each plane has a very different interpretation of what that might be, be it freedom, randomness, primal chaos, simple lack of order, etc.

Arborea, the Plane of Passions and Revels

Arborea is eclectic enough that I'm not really happy with the soundbyte I've got for it, but it seems to fit a good portion of the plane's character. Suffice to say that a staid, calm cutter is more likely to want to make a different plane his home.

Ysgard, the Plane of Glory

Limbo, the Plane of Primal Chaos

The Anarch advantage and the Chaos Shaping skill are covered in the Characters chapter.

Pandemonium, the Plane of Madness

Characters should make periodic Will rolls to avoid moving from one stage to the next in Pandemonium's sequence of madness. Optionally, a critical success on the Will roll will move the character down a level on the sequence of madness. The first three stages may be represented as temporary GURPS disadvantages, that last until the character progresses to the next stage or leaves Pandemonium:

1.  
2.  
3.  

At the fourth stage, the character should make another Will roll. The results of this will roll determine what permanent madness he picks up:

• Made by more than 2: -1 point Quirk [*]
• Made by 0-2:-1 point Quirk
• Missed by 1:-5 point Mental Disadvantage [*]
• Missed by 2-3:-10 point Mental Disadvantage [*] or -5 point Mental Disadvantage
• Missed by more than 3:-15 (or more) point Mental Disadvantage [*] or -10 point Mental Disadvantage
• Critical Failure:-15 (or more) point Mental Disadvantage

Those disadvantages marked with a [*] only manifest themselves while the character is in Pandemonium (this is a -xx% Limitation). The disadvantage should be chosen by the player. The GM should allow a player to choose a disadvantage worse than what the results of the Will roll would indicate, if the player so desires.

The GM should consider giving some sort of "affinity for the plane" bonus to characters who come in to Planescape for the first time already possessing some sort of appropriate madness.

The Abyss, the Pit of Terror and Pain

Planes of Law

The planes on the left side of the Great Ring all share, to one degree or another, an affinity for order.

Mount Celestia, the Plane of Individual Perfection

Arcadia, the Plane of the Common Good

Mechanus, the Plane of Regulated Order (the Plane of Clockwork)

Delon-Estin-Oti: The militia of this town fights with +4 to fighting skills (including Tactics), +2 to all defense rolls, and +2 to Move when determining order when their opponents have the Honesty disadvantage, have 2 or more points in the Strategy and/or Tactics skills (or other seemingly appropriate conditions). They fight with -2 to fighting skills and -1 to all defense rolls against opponents who have the Beserk (or other appropriate) disadvantage. Against most folk, they fight according to their natural skills.

Acheron, the Plane of War

Baator, the Pit of Oppression

Planes of Conflict

Bytopia, the Plane of Industriousness

Elysium, the Plane of Peace

The Beastlands

This plane doesn't need a soundbyte, because it's name is quite descriptive enough.

Gehenna

The Gray Waste, the Plane of Despair

Carceri, the Red Prison, the Plane of Treachery

The Outlands

STILL NEEDS TO BE UPDATED FOR GURPS/4E. Some of the ring definitions will change to use that very handy "number of prerequisite" column in the table at the back of the new edition of GURPS Magic.

The nine rings of spell annulment on the Outlands require some thought to convert to GURPS, since GURPS does not have nine "spell levels" as does AD&D. Instead, different rings have two kinds of limitations on spells. Inside the ninth ring, spells which have a prerequesitive of a certain level of Magery won't function. For instance, on the 8th ring and inside, no spells which require Magery 3 will work. The second limitation is on the base cost of the spell; as you get closer to the Spire, only less and less costly spells will work. This cost is only the base cost for Area spells; in other words, spells which require huge energy may be cast, but the 1-hex cost of that spell must be below the limit. (One side effect of this is that it will tend to make the fabrication of magic items impossible on most of the Outlands. What enchanting is done happens either on the 9th ring, or in Sigil.) Most magic items which emulate spells with an energy cost will suffer the same limitation, although, ineffably, at the whim of the GM, a magic item will fail on a ring further in or out than expected. "Always On" enchantments such as Puissance and Accuracy generally don't fail until the 1st or 2nd layer.

In addition to the table listed below, for rings at or inside the 8th, spells which are at the boundary for Magery prerequisite, or within 10% of the limit on base cost, will be cast as if in a Low Mana zone. So, for example, in the 7th and 8th ring, all spells with a prerequisite of Magery 2 will act as if they are being cast in a Low Mana zone. At the 3rd ring and inward, it's a Low Mana zone for all spells, and spells with any Magery prerequisite fail altogether.

Naturally, if not explicitly listed, a given ring includes the limitions of all rings outward of it. All of these numbers are subject to change.

RING	Max Magery Prereq	Max Base Cost	Other Effects
9th	(any)	(any)	none
8th	Magery 2	20	none
7th	Magery 2	16	Max Psionic Level: 10
6th	Magery 1	13	Max Psionic Level: 5
5th	Magery 1	10	Illusions, energy draining fail; powerful "super" abilities fail
4th	Magery 1	7	Poison neutralized; Max Psionic Level: 2
3rd	0	5	Demigod powers fail, no conduits; Psionics fail; most "super" abilities fail
2nd	0	3	Lesser powers annulled; no astral connections; all "super" abilities fail.
1st	0	2	Intermediate powers annulled
Spire	All Magic Annulled		All Supernatural powers annulled

Sigil

The Inner Planes

The Astral

The Ethereal

Ethereal Sickness: Roll against HT upon entering the Deep Ethereal, to avoid the disorientation of Ethereal Sickness. If you fail, you are at -2 to DX and IQ and all associated skills for the duration of your stay in the Deep Ethereal.

Increased Move: (A Guide to the Ethereal Plane, p. 19). Roll against HT, minus the difference between the desired move speed and one greater than your normal move (including encumberance), for each minute you spend moving at the increased rate. Failure means a loss of 1 HP.