
[This thread is for in-character general knowledge of Hell. Assume that anything in here is Canonical. It is therefore allowed for any player to use this material as true and universally known. Don't put it here if you want it kept secret. I will also use this thread to post information that is known to all players, as it is known.
The first post will include a current summary of all that is known. Later posts will include specific things that are added or changed, but this first post should reflect all of those things.]
[It should be pointed out that things in this thread or in turn results are not guaranteed to be absolutely right. Perhaps you are mistaken about something, and I include that mistake in your results. Perhaps there is a commonly held belief that is nonetheless wrong; I'll include it here as fact. Question everything.]
The Nature of The World
So, let us presume that there is a universe. It has a Creator, who made the world intentionally, following some design known only to Him. (The Creator is given the masculine pronoun, which is always capitalized. Decide for yourselves if this represents a true gender, or if I'm merrily following the rule of English grammar that requires me to default to the masculine in cases where true gender isn't known.)
The world includes various sections:

Heaven - where the Creator is said to reside

Hell - where the Creator is said not to be.
In concrete terms, the only difference between Heaven and Hell is that the Creator is present in one, and not the other. This is not an academic difference, as the mere presence of the Creator causes various effects on the state of Heaven as compared to Hell.
Heaven can be further divided into two sections, the Celestial Realm and the Firmament.
The Firmament, also known as Earth, is the physical realm where the souls of the living use their physical forms to act out the course of their lives. The Creator is present on Earth as well as the Celestial Realm, and so both are still considered Heaven.
The Celestial Realm, in addition to housing the Creator, lacks a physical component. Only those souls who have cast off their physical bodies may be present there. In addition to a required lack of body, souls must be free of anything ugly to the Creator's eye. The quality of something being ugly to the Creator is known as Sin. Through their decisions, souls may acquire Sin during the course of their mortal existences. The specifics of what constitutes Sin are known only to the Creator, though observation and conjecture do point to certain broad categories.
Once a soul has cast off it's physical shell, there is nothing to anchor it to the physical world. Souls without Sin are then free to enter the Celestial Realm, where they may presumably find some benefit (ecstasy, perfect knowledge, the rumors are many). Souls who are tainted by Sin, but lack a physical body are repulsed by the Creator. Since there is only one place for them to be repulsed to, all such souls end up in Hell. They remain in Hell until such time as they are no longer tainted by Sin, however long that takes. As with the nature of Sin, the exact methods to remove Sin from a soul are still unknown, though some gross theories are generally considered to be true.
Hell is divided into two sections, or perhaps more, depending on your point of view. The tendency is for souls with a different type of Sin near each other. It has been observed that in one section of Hell, the souls experience what they perceive to be suffering, with groupings of similar sins often having similar suffering. Some theories claim that the other section (where there is no suffering) has the subtle suffering of not experiencing whatever benefit is derived by those souls in the Celestial Realm, whatever that is. Since no knowledge of what that benefit could be exists outside of the Celestial Realm, nobody in Hell can really say for sure.
Denizens of Hell

It is known that, in addition to the souls, beings with limited perceptions who begin in physical form and then shed their shells to become entirely spiritual, the Creator created servitors. These are not so much beings as conditions. All the nature of the world, all the rules of physics and the rules of metaphysics are the result of these conditions. The tendency of massive physical objects to draw together, called gravity, is because of some servitor of the Creator which enacts that facet of the Creator's plan. The tendency of tainted souls to be repulsed from the Creator is also that. Some servitors appear to physical souls as the shells of other souls, perhaps to overcome the physical soul's inability to otherwise know the thoughts of the Creator. It is generally believed that these servitors lack free will, which among other things includes the ability to acquire the taint of Sin. Lacking free will, these servitors merely enact a purpose. They do not possess individuality, and do not communicate amongst themselves. Only when interacting with souls do servitors communicate at all.
In Hell, the tainted souls must somehow be made to suffer, in such a way as to free them of their taint, so that they may again enter Heaven. This task falls to the servitors called Demons. For some flavors of suffering, this requires that the Demons embody some kind of shape. It is for this reason that Demons have a form, which has been observed to be similar to the forms given by the Creator to both souls and to those servitors in Heaven who also enact the Creator's will. Draw from that what conclusions you will.
When is Hell not Hell?
The above state of affairs has existed. Servitors do not think, so they do not perceive. They have no sense of "how long", so all that can be said is that this is how the world was, because they know it to be true. Then, something happened.
If the very definition of Hell is that it is the place where the Creator is not present, what happens when the Creator comes to visit? When all the souls in Hell (and some of the suffering servitors as well) are there simply because of their inability to approach the Creator while weighted down with Sin, what happens to all of the tainted if the Creator enters Hell?
Nobody knows. It is generally believed that this is what happened, however. This is based on the interpretation of things said by some of the souls who recently (but still after 'the event') entered Hell.
The nature of Hell was changed, in ways that are not fully understood. Perhaps it was changed in ways that cannot be understood. And even now that the Creator has again left Hell (some would say "Now that this place is again classified as Hell by the Creator's absence."), some things continue to be changed. Some of the souls in the section of Hell that may or may not involve suffering claim that other souls who they remember being there before the event are no longer present. Since souls may become freed of taint at any time, who can say if these souls are gone as a result of the event, or just because they had suffered enough?
And the nature of Demons was changed as well. At least for some. They have somehow acquired some measure of free will. They think. They perceive. They remember. (A corollary of memory is that they now perceive the passing of time.) They communicate. Not all Demons are thus effected; only a very few, in fact. These elevated Demons are known as the Princes of Hell or Demon Princes. (Which proves that in thinking, they also have ego. Self-awareness comes with a judgement of relative value between "me" and "not me".)
These demons have looked around their world, and they have learned some few things, including all of the above.
The Paradox of Fallen Angels

Somehow, several of the Creator's servitors from Heaven managed to acquire the taint of Sin. As a result, they have been repulsed from Heaven into Hell. As with some of the souls, they are not being made to suffer. Without free will, it's unclear how they could Sin, or how suffering could free them.
Movement
There has never been a reason for Demons to move. They existed to bring suffering to the souls, which moved away from the Creator until they reached the appropriate part of Hell. Some time later, the souls would rise towards the Creator, free of Sin. However, by dint of their humanoid forms, demons may walk upon the soil of Hell as living souls walk upon the soil of Earth. Some demons have wings, and they may fly through the air.
Communication
Physical beings make sound in space. They make gestures. They ascribe meaning to these things, and use them to communicate ideas. This same metaphor applies to the interaction of being in Hell. Demons do not communicate as such, though they will sometimes give off noises and gestures that souls choose to believe have meaning. Demon Princes, as beings of free will, now also use these methods to communicate. While normal servitor Demons do not generally respond to the noises or gestures of souls, it has been found that when Demon Princes attempt to communicate with demons, they generally receive responses. In many cases, the Demons will obey commands from Demon Princes. Thus far, those commands have been limited to minor acts, along the lines of changing the nuance of how that particular Demon was giving suffering to a particular soul. None have attempted more drastic orders, as the idea of going against the purpose of Demons is still unusual to the Demon Princes.
Shouting - Demon Princes may communicate with all of the demons of Hell at once. Souls are too engulfed in their own pain to be aware of these shouts.
Regardless of what languages they spoke in life, all souls may communicate with each other, or with Demons. When they're not screaming in anguish, of course. There seems to be only one language in Hell, even when souls are attempting to obfuscate their meaning.
The Effects of Free Will on Hell
Demon Princes have noticed that as they continue to administer suffering to souls, in the same manner as they had been doing before becoming Princes, they will acquire some of the taint of Sin from the souls. They do not know exactly how much, or why, but they certainly notice that the taint of Sin stays with them instead of the soul. They also notice that they can make changes, and that doing consumes the taint. So far, only minor changes have been made: the shape of a flame used to burn a soul, or the color of the chains in a flail. Perhaps with even more Sin, greater changes could be possible? Servitor Demons also acquire the taint of Sin as they administer suffering to souls. Lacking free will, they have not chosen to use it to change anything.
Of note on the quality of Sin, is that while all Demons seem to acquire it from administering suffering, and while the Demon Princes may move it around, acquire it from servitor Demons, or consume it in enacting change; there seems to be no Sin present in Hell from prior to the event. One assumes that however long the world existed before the event, souls were in Hell, suffering, and being freed of their Sin. None of that Sin is present. There are no stockpiles of ancient Sin lying around, waiting for newly sentient beings to use it to alter the world on a huge scale.
Infernal Bestiary
The Princes of Hell
Abdul Alhazred - Ruler of the Necronomicon
Andramelech - The All-Encompassing Sky
Buriax - Ruler of the Labyrinth
Ghaenum - Father of Truth
Iblis - The Unpunished
Iztet - Ruler of the Flower
Nybbas - The Chronicler of Hell
Pazuzu - Father of Lies
Philatanus - Ruler of the Cauldron of Blood
Sonneillon - Ruler of the Palace in the Sky
Tharrcixifuge - Ruler of the Pits of Despair
Zafmael - The Flame
Zepar - Ruler of the Fortress of the Elements
The Lords of Hell
Azazel - Lieutenant to Zepar
Dragon - Lieutenant to Philitanus
Gardener - Lieutenant to Iztet
Herald - Lieutenant to Iblis
Kasdeya - Lieutenant to Zepar
Oinodaemos - Lieutenant to Tharrcixifuge
Paymon - Lieutenant to Zepar
Wonko the Sane - Loosely tied to Iblis
Xsu - Lieutenant to Tharrcixifuge
Xsu 2 - Lieutenant to Tharrcixifuge
Xsu 3 - Lieutenant to Tharrcixifuge
Yeter'el - Lieutenant to Zepar
Shadow Fiend 1 - Lieutenant to Sonneillon
Shadow Fiend 2 - Lieutenant to Sonneillon
Shadow Fiend 3 - Lieutenant to Sonneillon
Knights of Hell
Alchemist - In Service to Alhazred
Balor - In Service to Alhazred
Hand of Iblis - In Service to Iblis
Human Demon - Loosely tied to Zafmael
Lamia - In Service to Sonneillon
Overlord - In Service to Tharrcixifuge
Sarlac - In Service to Tharrcixifuge
Tormentor - In Service to Iztet
Wyvern - In Service to Philitanus
Air Legionnaire - In Service to Zepar
Earth Legionnaire - In Service to Zepar
Fire Legionnaire - In Service to Zepar
Water Legionnaire - In Service to Zepar
Commoners of Hell
Air Fiend - Zepar's Elemental Warriors of Air
Angel Armor - Sonneillon's Fallen Angel Soldiers
Djinn - Iblis' Missionaries
Drone - Most basic form of demon
Earth Fiend - Zepar's Elemental Warriors of Earth
Fallen Angel - Banished Angels from Heaven
Fire Fiend - Zepar's Elemental Warriors of Fire
Nephilim - Abdul Alhazred's elite warrior cadre
Pit Fiend - Winged, horned, hoofed, warriors of Hell
Sentinel - Iztet's Guardians
Soul - What's left of a mortal after death
Soul Armor - Sonneillon's Soul Soldiers
Succubus - Wonko's Basest Needs
Unpunished Soul - Souls who are not tormented in Hell
Water Fiend - Zepar's Elemental Warriors of Water
Air Centurion - In Service to Zepar
Earth Centurion - In Service to Zepar
Fire Centurion - In Service to Zepar
Water Centurion - In Service to Zepar
Beasts of Hell
Angel Worm - Philitanus' pets enjoy eating angels
Cerberus - Buriax' guardian beasts
Chiropterror - Tharrcixifuge's shock troops
Hell Hound - Buriax' guardian beasts
Maggot - Andramalech's pets
Mane - Tharrcixifuge's suicide troops
Soul Worm - Philitanus' pets enjoy eating souls
Artifacts
Divine Raiment
Encyclopedia Infernalis
Crystal Seeds
Energetic Portal
Infernal Armor - Worn by the Gardener
The Rake - Carried by the Gardener
The Scimitar - Carried by AlHazred against the Gardener
Soul Cage - Fashioned of damned Souls, can even hold an engaged angel at bay.
Soul Net - Fashioned of damned Souls, nothing can escape its grasp
Geography
Due to the changes wrought by Andramalech in the 12th Decade, Hell is a vast and empty space. Above Hell is the Creator, and dying Souls fall into Hell from Heaven.
At the top of Hell are Andramalech's two faces in the sky. At the bottom of Hell is the Flower. Everything else floats in islands of stone, large or small, somewhere in between. Distances are so vast, that even if any two islands were directly above or below each other, it might take decades to fall from one to the next closest. However, no two islands are directly in line, with one exception. Since the Flower is the absolute bottom of Hell, falling from any island will eventually take one to the Flower. Such a fall from Andramalech's mouth could well take many centuries, but one can rest assured that eventually the fall would stop.
From Top to Bottom, here are the islands of Hell:
Andramalech - His two faces look down upon all of Hell from the sky, as they have done for decades. His Black Cloak of Office can be seen in all directions.
The River Phlegathon - Andramalech's tears of rage rain down upon Tartarus.
The River Lethe - Andramalech's tears of sorrow rain down upon the Labyrinth, then continue on to variously douse all other parts of Hell.
The Labyrinth of Buriax - Home to the Praetorean Councilors of Buriax, who assign all Souls to their places in Hell.
The Island of the Unpunished - Tartarus is a city for Souls. Home to the Unpunished.
The Information Office - For information about interacting with the Praetorean Councilors of the Labyrinth, please see the Information Office.
The Pen Islands - These otherwise empty islands contain pens where once Souls waited to be collected by the Princes of Hell.
The Island of Humans - Home to the quixotic "Human" demons.
The Asylum - Home to Wonko the Sane and his Succubi.
The Islands of Rent Souls - Home to the most pitiable Souls in all of Hell.
The Islands of Chanting Drones - Home to nothing but drones, chanting the Word of Pazuzu.
The Necronomicon - First City of Hell, which rests exactly in the center of the Infernal depths. Home to the mighty Balor.
The River Acheron - Mighty river of agony and ecstasy that binds the major islands together.
The Cauldron of Blood - Home to the Wyrms of all kinds.
The Palace in the Sky - A sky within a sky, and a palace within a palace.
The Battle Island - A place to fight. Home currently to the Lamia.
The Fortress of the Elements - Home to the four types of elemental demons.
The Pits of Despair - Home to the Overlords.
The Flower - Home to itself, the Flower is the island. There are no denizens except the Souls who feed it.
Pandæmonium - Little is known about the Grandest Edifice in all of Hell. No such island has so far been found.
The Firmament

Save perhaps demons, all inhabitants of Hell first began in Heaven, where the Creator is. Most of them, all save the fifty Fallen Angels, began as mortals in the Firmament. Much like Hell used to be, the Firmament is a flat place occupied by mortals. There are, however, several key differences.
The Firmament contains much more water than Hell. So much so that it became necessary for mortals to learn to traverse the water to interact with each other. Except perhaps for Zepar's water fiends, no demon in Hell is really prepared to deal with water of this magnitude. Also, there is much more than just mortals there. Animals, plants, and a huge assortment of various types of resources for the mortals to use. Demons create weapons from raw harvested Sin, and simply create the weapon. Mortals would take the dead carcasses of plants or animals, or pieces of stone from the ground, and blend them together somehow. Melt down certain types of earth, and it can become much harder than earth, and as sharp as our claws.
There are 22 nations in the Firmament, made up of groups of mortals banding together against each other. The few Souls I have questioned on the subject seem to believe that the ruler of each nation is chosen by the Creator, because the previous ruler was also chosen by the Creator.
Strange to our way of reckoning direction, all parts of the Firmament are equally close to the Creator, since the Creator is present in all of them. So, instead, mortals figure location based on an arbitrary choice. So, at the top of the above map, which they declare to be "North", and to the left of the map, which they declare to be "West", lies the nation of Illyria. All the others are similarly described.
Nations in the Northern Alliance
Illyria -
Macedon -
Thrace -
Chalcidice -
Nations in the Eastern Group
Aeolisionia -
Phrygia -
Mysia -
Lydia -
Caria -
Rhodes -
Nations in the Western Group
Epirus -
Thessalia -
Euboea -
Aetolia -
Boeotia -
Nations in the Peloponnesus
Achaia -
Argolis -
Arcadia -
Laconia -
Messenia -
Ells -
Nations in the Southern Area
Cyclades -