And for anyone who might want to actually adopt this dungeon for use in their RPG, I offer this:

DUNGEON KEY

The approach to the Living Dungeon* is largely explained in the texts above. It should be noted that vines and roots, along with bits of other growth, are fairly plentiful along the slopes down to the roadway. The forest may be of any type suitable to the region in which the GM places the Living Dungeon, but it should be fairly thick woods, offering plenty of cover for ambushes and easy travel from tree to tree above the forest floor for the natives. (* - To be referred to with a capitalized ‘Dungeon’ when referring to the intelligent entity, but sometimes as plain ‘dungeon’ when simply referring to the structure.)

In general, except for the stairs leading down to rooms 20 and 21, as well as the final section with stairs and landings, the dungeon is modestly sloped, such that it would not normally be noticed except by those making something like a engineering skill check or having an innate sense for underground passages. It is just enough to allow water to flow as desired. Each and every room has an opening in the ceiling two or three inches across through which water may be pumped. In theory, this could be used to drown intruders, but the Dungeon has never done this. The purpose is to wash materials to the acid pit in room 48 and out the rear of the dungeon. Thus the slope is down toward the center path (from 1 to 64) from the sides of the dungeon, and it is also sloped down from front to back.

The few permanent features are here described normally. The usual stock of creatures and treasures changes over time, and the Living Dungeon may easily be tuned to be suitable for novice to nigh-godlike individuals by adjusting the residents (and, if need be, the Living Dungeon’s capacities with regard to room 20 especially). [In order to facilitate speed of adapting this dungeon to play in the system of your choice, suggested contents for rooms is placed within square brackets like this text. These entries are but suggested possibilities to help the busy GM along. While some will connect together, there is no overall plot to them and they may be used in part, while other sections are ignored.]

1. The entrance to the Living Dungeon is a little castle gateway flanked by two small towers, but there is no castle behind it, only an entrance into the earth. There is also no door or gate to bar the entrance. The look of it somewhat suggests a face, with the tips of the towers as pointed ears, two firing slits suggesting eyes above the gaping mouth of the gateway. One might even fancy the meadow grasses beyond as hair above the crenelated brow.

Inside, there is a portcullis, which will be raised initially. The mechanisms are buried inside the earth and were magically sealed in stone, so while it is theoretically possible to dig them out, this is a job more suitable for a mining company than a band of adventurers (and the noise would surely draw attention). It was intended that the Living Dungeon should have sole control of this gate. Once all have passed inside, the portcullis will lower and lock in place. If there is a reluctance for all to enter, the Dungeon will usually try to draw those still outside into it, but if this does not work, it has no problem splitting the party.

Just beyond the portcullis is a grate across the width of the corridor. When it rains, water flowing in is drained through this passage and used in the Dungeon’s water circulation system. Through mechanisms that are buried and controlled by the Dungeon, the drain can be closed to let water flow on into the dungeon normally. This is a narrow passage, and characters who cannot fit through a two-inch slot will not be able to invade the water system.

Past the grate is a beautiful red carpet, the Dungeon’s metaphorical tongue. If it is removed from the corridor, or destroyed, the Dungeon loses the power of speech until it is replaced.

Not far beyond that is a bladed pendulum trap. The Dungeon can elect not to have it trigger, but rarely has a reason to do so. It can also reset the trap when it wishes, but will not do so while the trap is being observed. If the pendulum is examined once it comes to rest, an inscription may be noticed, reading “uvula” in whatever language the GM thinks is most suitable for Aklov.

2. This room generally is either empty or contains some creature(s) that came in for temporary shelter. It contains the first interior door that will be encountered. The doors vary in size, but all are of solid wood, normally opening easily. The Dungeon, however, can open and close all doors and may cause them to jam shut (this is largely to control the air circulation and sometimes water flow, but it may be done to play with intruders). The doors do not move with any great force, and normal precautions can ensure that a door stays open or shut. Creatures that take up residence and have the capability of doing so sometimes add locks, bars, bolts, and/or door traps to secure their territory.
This room is also where the surfaces change from the “finished castle” look of the entry corridor to the rough and unfinished look of the rest of the dungeon (though the floors are smooth to assist with moving materials through).
[A frightened fox, who will growl in a corner, attacking only in self-defense.]

3. [A small scatter of coins may be found with successful perception. They recently fell out of a hole in a pocket.]

4. [Empty]
From here or from room 5, explorers will become aware of a rhythmic mechanical thump. Following the sound will lead them to room 7. The sound can be heard at varying distances, depending on whether or not doors are open at the time. If rooms 9 or 23 are between a location and room 7, that location will have the thumping of room 7 drowned out by the noise of the air circulation machinery, but otherwise, given open doors all the way, the thump can be heard softly to edges of the dungeon down to the bottom of the steps to room 65.

5. [Two bodies, killed in the last day or two. Looted.]

6. [A family of rabbits lives here. They venture out into the woods whenever they like, being small enough to fit through the portcullis even if it is lowered. They shelter here, safely, because nothing in a dungeon of any intelligence at all trusts a soft, fluffy, little bunny to be what it seems.]

7. This room is the beating heart of the Living Dungeon. A large machine with many pipes connecting it to the back wall, the floor, and the ceiling continues a steady pumping, controlling the fluid flow throughout the dungeon.
Attempts to interfere with this machinery face the risk of setting off various traps, some of a simple mechanical nature, others spouting hot steam. The pumping machinery is of sturdy construction and is not easily tampered with. Water is doled out as needed to keep dungeon inhabitants hydrated, to flush debris to room 48, and to flush out the whole dungeon down corridor 64 on out through room 67.

[A ceiling-crawling predator lurks here, knowing that the pump will draw attention to itself, away from the predator, making ambush easier. Use a giant spider if your system doesn’t offer any more interesting obvious choice.]

8. If the door to room 9 is open, a warm breeze will be felt from that direction. The noise from room 7 (Thump! Thump! Thump!) is quite loud here, even with the doors closed.

[Someone not careful may step into a pile of rabbit droppings.]

9. This is another room dominated by machinery. Here, the large machine connected to floor and ceiling by multiple pipes is combined with a set a large rotating fans. Less noisy individually than the great pumping station in room 7, the collective noise of these machines is still considerable and will penalize attempts to listen to other sounds.

The central unit does move some air, but it is mostly a heating unit, and this room provides warm air to heat the dungeon when needed. Like the water pump, it contains some traps to discourage tampering. The fans are not trapped, but they are rapidly-moving steel, and anyone stupid enough to slip a hand through the metal frame that holds one will risk serious damage to that hand.

[One humanoid, keeping watch, who will try to slip away down corridor 10 without being noticed. If he succeeds, the humanoids in rooms 11-19 will be alerted to the intrusion and surprising them will be impossible. If they are given time, they will organize their defense.]

[A sort of grill has been set up next to the central unit, drawing heat off of it to create a cooking surface. It is here that the humanoids do what cooking they require. A pair of tongs, a flipper, and a cooking fork hang by the grill.]

10. [This corridor is empty, though there is graffiti scrawled on the walls with chalk. It is in the language of the humanoid race that occupies this section of the dungeon and is mostly silly insults, boasts, and stupid jokes. The humanoids can be goblins, orcs, or similar beings suitable to the setting. They can even be a group of human bandits. If the player-characters are strong, the humanoids can easily be upgraded to something like ogres.]

11. [Guardroom. Half a dozen humanoids hang out here “on watch”. A table and chairs provide a place to gather while not under attack, which is almost all the time. They have a few decks of cards, maybe a simple board game that supports wagering. Each has a pouch of coins on his person. These guards will be in armor and fully armed. Additional weapons and shields are stored in this room. The chief guard has a horn which he will blow to signal the rest of the population if they are attacked without warning. If the watchful guard from room 9 is able to give warning, then he continues through to room 15, while one of the guards here briefly jogs down to room 17 to spread the alarm before returning to his station. If the guards are surprised, they will be in the middle of a card game. If approached in a friendly manner, they would be happy to gamble with strangers, though there is a 25% chance that it will turn out that they use a marked deck that they all know for this purpose.]

[This room is also the food preparation area. One corner contains another, smaller, table and some food stores, plates, cups, and some kitchen utensils.]

12. [Barrels are used to collect water here, while a small tub serves as a wash area. There are towels and soap.]

13. [Sleeping quarters. There are beds here for eight of the humanoids, as well as a pair of wardrobes and a chest of drawers where some spare clothing and minor personal effects are kept. If you want a cheap used comb, this is the place to loot. There is a small bag of coins hidden under one bed, as the watcher in room 9 does not carry anything that can jingle. One humanoid sleeps here if not alerted, armor scattered on the floor and a dagger as his only weapon.]

14. [There are several chamber pots in this corridor. When they start to get full, some unlucky humanoid gets the job of hauling them to room 48 to deposit in the acid pool. After one failed to return from this mission, the actual practice has become the throw the contents into room 48 as quickly as possible, leaving the matter of getting the waste material into the pool to the Dungeon.]

15. [Residence for six more humanoids, similar to room 13. Five humanoids are present, unless there has been time to organize defenses. If surprised, they will not be wearing their armor, which is neatly piled on the floor. Each wears a coin pouch and a dagger. One wears an eye patch and fights a bit better than the others. If the eye patch is removed, a gem is discovered stashed in the empty eye socket.]

16. [Like corridor 14, a few chamber pots are stored here, though there are also some herbs in a vase and a little stone stool where ashy residue shows some have been burned there as well. This attempt does improve the smell. Some.]

17. The secret door here is well-concealed, and once it is detected, another roll is required to locate the opening mechanism (a small secondary secret panel that conceals a button to open the door). This door is rarely known to any dungeon inhabitants and is usually missed by intruders. A faint mental suggestion results in the door here typically being covered by any furnishings that would do so, making the door completely hidden unless those furnishings are moved.

[There are a large bed and two smaller beds in this room. A wardrobe conceals the secret door. There are two small chests, a dresser, and a small table. One chest contains a modest stash of treasure, the other assorted items of moderate value kept because one of the inhabitants thought they were interesting. This is the bedchamber of the humanoid leader and two bodyguards. The bodyguards are somewhat better fighters than the norm, while the leader is the best fighter in the group and has some superior equipment, magical if suitable. Even if not alerted, one of the bodyguards will be armored up, and all have good weapons at hand. If not alerted, there is a 50% chance of 1-3 females in the room.]

18. [Barrels are used to collect water here, while a small tub serves as a wash area. There are towels and soap.]

19. [Beds are here for nine female humanoids. This room is a bit neater than the rest and decorated a bit. Three wardrobes and two dressers contain extra clothes and personal effects. The females wear daggers and coin pouches. If not surprised, they will have short swords ready, but these are otherwise kept in a rack near the door where they cannot be reached if someone rushes in.]

20. The secret doors become increasingly difficult to locate, as do the separate opening mechanisms as one progresses from room 17 to the secret door to the hidden chamber behind room 21. The stairs are steep and possibly dangerous if the intruders are heavily loaded. Anyone encumbered with excessive gear should need to make an appropriate check to avoid tripping and falling for minor damage on the way down.

The central object in room 20 is the “brain” of the Living Dungeon, a mass of shimmering crystals and glowing fungi. So long as this brain is intact, the rest of the dungeon can be quickly regenerated to restore it to its original condition after damage is done to the structure. Damaged walls or doors generally take no more than a day or two to return to normal (though the Dungeon allows modifications by residents to remain while these serve to make the residents more comfortable and happy). Restoring the machinery in rooms 7, 9, and 23 is trickier, taking up to a week if truly wrecked.

Within this chamber, the brain possesses substantial psychic powers, and it will attempt to obtain its own advantage, possibly negotiating and quite likely attacking with a suitable mental assault. Details will depend on the system used, but the Living Dungeon should be a formidable opponent in its brain chamber, and victorious parties should feel that they have defeated the Big Boss. It should also be noted that the brain itself is large and fairly resistant to damage.
If the brain is destroyed, then the dungeon will not regenerate. The brain itself can take anywhere from three months to a year to regenerate, depending on whether excessive damage is done to smash it beyond the point of “death”. However, so long as the soul of the Dungeon has remained intact, the brain will regenerate itself, at which point it will begin repairing the dungeon and probably plotting a scheme of revenge on those who dared do it harm.

21. This is the “secret treasure room” of the Living Dungeon, designed largely to distract successful intruders from the extremely-well-concealed secret door here. Ideally, having found the great treasure trove of the dungeon, the intruding party will leave in triumph.

[Coins, gems, and jewelry glitter in piles. Fine armor and weapons, some magical, are on display. There are some excellent art pieces and a small collection of additional magical items as the GM will allow.]

If the final secret door is discovered and opened, there is inside a black obelisk of exceptionally hard and dense stone, engraved with golden glyphs. It is difficult to damage, but cannot take as much damage as the “brain” before expiring. This is the “soul” of the Living Dungeon, the very heart of its life force. If the soul is somehow discovered while the brain still lives, then the soul can use magic to defend itself in an intelligent way. In all likelihood, however, it will only be uncovered if the brain is already “dead”, in which case it has only an automatic response. As soon as the secret door is opened, the obelisk crackles with power and releases an electrical discharge through the doorway so long as there is any target available. This is relatively low-powered compared to what it could accomplish with spells when the brain guided it, but it should still be a threat to a party weakened by the fights on the way here.

22. [The middle twenty feet of this corridor are scattered with caltrops.]

23. This is another room dominated by machinery. Here, the large machine connected to floor and ceiling by multiple pipes is combined with a set a large rotating fans. Less noisy individually than the great pumping station in room 7, the collective noise of these machines is still considerable and will penalize attempts to listen to other sounds.

The central unit does move some air, but it is mostly a cooling unit, and this room provides cold air to cool the dungeon when needed. Like the water pump, it contains some traps to discourage tampering. The fans are not trapped, but they are rapidly-moving steel, and anyone stupid enough to slip a hand through the metal frame that holds one will risk serious damage to that hand.

[An ice viper shelters under the cooling unit and will normally only attack if this resting place is disturbed. It is similar to a normal serpent and statistics for those can be used with the following differences: the ice viper is not only immune to cold-based attacks, but is healed by them; it takes extra damage from fire/heat attacks; and its venom causes a victim that does not resist to be transmuted into ice.]

24. [Two dead ratmen lie here. Their bodies have already been stripped of anything of value.]

25. [A large gong is here, along with a striker for it. It has some value, but probably not enough to justify trying to carry something so large and heavy back to civilization unless magical assistance in that matter is available. Sounding the gong will alert the creature in 26.]

26. [This was a barracks of sorts, but it has been torn up, the bodies of inhabitants likewise shredded. The creature that did this is still here. Something with formidable physical powers and a bit of magical ability as well. A small dragon could do, or even a mutant tiger that shoots flames from its eyes.]

27. [A good supply of mundane weapons and gear is stored here, along with a small supply of coin. The door was provided a lock by the barracks inhabitants, which saved this stash, but did the inhabitants little good. The key was lost or destroyed in the slaughter, so access requires picking the lock or forcing the door or some less conventional solution.]

28. [A giant centipede is sleeping here. It will attack if it feels threatened, but will otherwise be non-aggressive.]