Each night, you spike shut the doors to the most defensible room you can find and, setting nervous watch schedules, slumber fitful and interrupted sleep for the scant few hours between the last hideous shriek from below and the moment your friend wakes you for your turn standing with spear in hand by the hastily-barricaded opening. Each night the dungeon awakens around you, the ruins breathing in and out in a noxious rhythm out of step with the world above. Creatures impure and volatile skitter and creep in the fissures where the crust of the world breaks through the ancient carved walls of this malevolent place. How many days has it been since you saw sun, or felt the cool eastern breeze, or heard the mournful songs of a bird in the verdant plumage of the living world? Ten? A hundred? A lifetime ago. The dungeon is the sky same as it is the stone beneath your feet; dark, dirty, deep. Each night, you struggle to refresh your weary body and mind, breathing slowly and softly with a helmet for your pillow. Each night, the dungeon breathes slowly and softly also, into you, into your lungs and your mind and body. Each night, you spike shut the doors to the most defensible room you can find and, setting nervous watch schedules, you drift away a little further from who you were the first day you set foot in this place, and when you awaken, you are new. The dungeon breathes new air into you, dark, dirty, deep.
The dungeon is a malevolent entity on its own, as set forth by people smarter than I. It corrupts. It is a cancer that changes everything it contacts. It means you harm if you descend into its depths; at best, you may hope it just wants you dead, because perhaps much worse it may want to add you to its horrific menagerie. For this reason, dungeons must be overcome and cleared of their aura of decay, and adventurers, driven by greed or duty, seek out such awful locales and struggle within their walls to spare the world around them from these horrors.
Sleep Mutations
At the end of each week spent in a dungeon, roll a test of 1d20 under CON. On a success, your character has the fortitude to fend off the mutagenic humors of the dungeon. On a failure, roll on the table below:
| 1d100 | Mutations |
| 1 | Left hand gains suction cups, like a starfish. Assists with gripping things. Makes it tough to drop things. |
| 2-3 | Third eye grows in the center of your forehead. More sensitive to bright light. Not much better at seeing in the dark. |
| 4-5 | Nothing this time – but you start to itch. |
| 6-8 | You no longer need to eat. Eating is deleterious to you; you will throw up any food you eat within 1d4 minutes of consumption. |
| 9-10 | Right pinky finger withers away and falls off, tingling all the while. |
| 11-13 | All fingernails fall out. They don’t come back. |
| 14-17 | Nothing this time – but you start to itch. |
| 18-20 | Lips grow together and must be slit open to resume normal speech (1HP loss) |
| 21-22 | Gain an allergy to wood; holding it in your hands or putting it in your mouth is painful. |
| 23-29 | Nothing this time – but you start to itch. |
| 30-34 | Right eye changes color to a different, but natural, hue. |
| 35-38 | Left eye changes color to a different, and unnatural, hue. |
| 39-41 | Face lengthens slightly, making you look slightly unfamiliar and suspicious to those close to you. |
| 42-48 | Nothing this time – but you start to itch. |
| 49-53 | Sneezing now releases a spray of spores that grow into small mushrooms rapidly before crumbling to dust just as fast. |
| 54-57 | Silver scalds you, as if you have become infected with lycanthropy or vampirism. You haven’t. Sensitivity fades in one week. |
| 58-61 | Cannibal urges fill your mind. Each time you slay a foe of the same species as your own, roll 1d20; on a 1, you must consume some part of their body. Can be cleansed through a clerical spell of curse removal. |
| 62-69 | Nothing this time – but you start to itch. |
| 70-71 | One foot lengthens and no longer fits your shoe. |
| 72-74 | Ears become shaped like a donkey’s. |
| 75-80 | Nothing this time – but you start to itch. |
| 81-82 | Eyes now blink sideways instead of normally. |
| 83-85 | Drool. A lot. Saliva is black or blue in hue. |
| 86-89 | Nothing this time – but you start to itch. |
| 90-91 | 1d6 small, stubby horns sprout from the forehead. Helmets and hats must be modified to fit or conceal. |
| 92-93 | Feet change shape to bird feet; shoes no longer fit but feet can grasp rods and lines with perfect grip. |
| 94-95 | Skin becomes slightly waxy. You are harder to grapple, but also harder to pull or rescue. |
| 96-97 | Nothing this time – but you start to itch. |
| 98 | Darkvision! Unfortunately, light vision has gone out the window; torch and candlelight are like knives to your eyes. Switches back in 1d6+1 days. |
| 99 | Left knee inverts. That might make it hard to wear plate armor, but it reverts in 1d6+1 days. |
| 100 | Nothing this time – but you start to itch. |
As adventurers are afflicted by these changes, the entries should be updated. If you’re feeling up to it you could make this into an immense list, a d1000 or something. There’s basically no limit to the number of mutations and mutation table entries to be found on the internet. There can – and probably should – be an endless array of unexpected changes big and small to reinforce the unnatural alien strangeness of the deep, dark dungeons below.