This is what I came up with, all within 60 minutes, which includes the map. I "have" cleaned up the text a bit, though. I don't want to ask anyone to understand my sketchy shorthand.
Note that my thought is that this would be used with a game system similar to the one I wrote about last Wednesday. The idea is that the players begin with no classes at all, similar to The Funnel of DCC RPG. As they play through this dungeon, they will seek to define their character.
GENERAL INFO:
Old man Herst recently pulled down a bunch of trees at the end of his property. His onions were profitable last year, and he'd like to increase his crop this year. While tilling the soil, though, he discovered the most peculiar thing: a stone stairway! Leading right down into the earth! It was the damndest sight he ever done seen, and when he was telling the tale down at the pub that evening, you overheard him.
It's perhaps 2 in the morning now, and you and your friends have gathered around the stairs. You've heard it said that treasures can sometimes be found beneath the earth-treasure enough that a bunch of farm hands like yourselves could buy a better life for yourselves.
ROOM 1: The walls and floor are a moss-covered flagstone. Stones are missing here and there, exposing the earth. The ceiling is almost entirely exposed earth, supported by stone arches which criss-cross the ceiling. Roots poke through here and there, and it looks as though it wouldn't take much for the dirt to collapse into the room. These conditions persist throughout the dungeon, unless otherwise indicated.
There's also a good deal of timber in this room, stacked in piles against the east and western walls. It is clearly old and rotten, perhaps part of the structure which originally stood over these stairs.
Exits to the North and South are visible upon entering the room. The secret exit to the West can be revealed by moving the timber aside.
There are 6 mouse-folk here, huddled in the corner and clutching their clubs. Their fur is mottled, and they appear to be malnourished.
ROOM 2: The walls have corpse shelves here, though most of these are empty. There are 12 shelves in all, but only three bodies remain. Close examination of any of the empty shelves will reveal a small pressure plate in roughly the same spot on each shelf. Pressing the plate does nothing. Close examination of the wall across from any shelf will reveal a small hole, the purpose of which is unclear.
Moving any of the three bodies which remain releases the pressure plate under their heads, and a crossbow bolt is fired at the player's back from across the room. Also under each of these bodies, roughly where the small of the back would be, is a small ovoid piece of amber. Each is worth 10gp.
ROOM 3: Some of the floor stones here have been pulled free, and water from above has formed into a pond which is 2ft deep at its deepest point. There are six mouse people here, drinking the water. Two more stand guard.
Aside from the water, there are three shelves in the room which were once filled with books. The shelves have now been knocked over, and the books scattered about the floor. Most are torn to pieces, and nearly all of them are covered in black mildew and small mushrooms. Thoroughly searching through the books will reveal only one book which is still in good condition. It is written in an odd script, but anyone who makes a successful intelligence check will strangely be able to read it.
Studying the book from cover-to-cover takes 8 hours. Once completed, the reader's mind will be awakened to magical power. The player may immediately become a 1st level wizard, and may use this book to prepare a 5lb "Mage Hand" spell.
Once someone has been awakened in this manner, the book must rest for 100 years before it can awaken another.
ROOM 4: Most of the stones from the walls and ceiling have been piled in the center of the room in a 4ft high mass. Mouse folk have burrowed small nests in the dirt here. There are 14 adult mouse people here, and 26 young.
Beneath the pile of stone is a small chest containing the treasures of the mouse people: 16 gp, 42 sp, 317 cp, and 1 ruby worth 25gp.
The secret door in this room is opened by pushing on a hidden stone, and can only be discovered by performing a search check on the appropriate wall.
ROOM 5: In the center of this room is a wooden chair with skulls piled up around the base of it. Several skulls are nailed to the sides and legs of the chair as well. A young man in black robes with skulls haphazardly sewn onto the shoulders is nervously pacing here. He is Hezaphezus the Malevolent Bringer of Doom and Unlife. An inept necromancer of 18 years. He already cast all of his spells for the day, but carries a dagger and a Wand of Cold, which deals 1d6 damage and has 1d10 charges. Also on his person are 30 gp.
ROOM 6: Eight shambling corpses are here, banging on the door which leads to room 5. If zombies can show emotion, these zombies are angry. They're so intent on getting through the door that they will not pay attention to the players unless they are attacked.
The flagstones on the floor of this room make a spiral pattern which twists towards the center of the room. At the center of the floor is a glass lens, about 1ft in diameter. If you look through it, you will see the plane which your soul would be bound for if you died today.
ROOM 7: This is the lair of the Spidersnake. The room has no obvious features upon entering. However, it is bisected by the web of the spidersnake, and anyone attempting to move from one door to the other will become tangled.
The spidersnake itself rests in a web funnel it made in the ceiling of the room. Among the bodies in this funnel the players can find 40 sp, 8gp, and a sword whose blade always seems to be covered in a thin layer of green slime. This is a Sword of Rotbane, which sets fire to any undead it successfully strikes.
ROOM 8: A statue on the Western wall stretches an arm straight out, pointing at a spot on the floor. The statue wears a crown. If the base of the statue is inspected, the players will find writing which reads only "The Pretender."
Any player who kneels before the statue will cause a crossbow bolt to fire from the tip of the pointing finger.
STAIRS: The dungeon descends further downthough to what I have not yet determined.
Credit: thelema-and-faith.blogspot.com