People keep asking for "beginner" dungeons. Everyone can name "classic" dungeons - Tomb of Horrors, Barrier Peaks, Ravenloft, etc. - but in order for those adventures to make sense, there needs to be some sort of introduction.
It's like all the adventures we have are Bach concertos. People keep writing amazing works of staggering genius, but someone needs to write a book on how to play the piano.
I had the same questions, and since I couldn't find anything satisfactory, I decided to write the kind of dungeon I would have loved to find. I wanted to write the best basic OSR dungeon for beginners that I could, and I also wanted to show the design process.
If you like this dungeon, please share it, tell people about it, print copies and leave them lying around local game stores, or email this post to friends who have "always wanted to try D&D but don't know where to start". The entire thing is and always will be free.
The maps aren't printed with grids because I think it's important to redraw them yourself. There's something of value in it. As you redraw them you'll make changes or mistakes, and the dungeon will become your own. You'll get a feel for how to draw your own dungeon.
The encounters aren't balanced. They don't have difficulty ratings. There are few rewards for fighting.
There might be stuff in this dungeon that you disagree with, especially if you're an experienced GM. That's fine! It's designed to be modular and hackable. Move stuff around. Remove things completely.
Treasure amounts are a balanced around the idea that 200gp is enough to level a single character. By the end of this dungeon, surviving PCs should be level 2 or 3, assuming the usual rates of attrition, loss, and panic. Damage is scaled around PCs having between 4 and 16 hit points. Otherwise, I've tried to make the module as system-less as possible.
The generic OSR introduction I've written here might also be useful.
Boss Fight: the Stone Cobra Guardian
Boss Fight: the Basilisk
PDF Version. If you notice errors, post a comment. Current version is 1.0
Playthroughs and Reviews:
My group: Session 1, 1.5, 2, 3, 4, 5, 6,
Throne of Salt: Session 1
GG NO RE: A podcast! Session 1, 2
Arnold K: "Hey, this actually seems like it would accomplish its goal of being a teaching dungeon. I like it."
Daniel Davis: "Ran this tonight, modded it to fit my setting. Half the group was new to D&D. Worked perfectly as tutorial dungeon."
Ten Foot Pole: Worth reading the full review. 11/22, but based on the barebones and haphazard v.1.0
Tomb of the Serpent Kings is a buried dungeon with three levels and four main thematic areas. I've included very minimal descriptions in the dungeon itself. You will need to come up with room descriptions on your own, in your own style. The note below might help.
Mechanics and Lessons:
Level 1: The False Tomb
Introduces the very basics of dungeon design and exploration in 7 rooms. It's just the right length for a first session, assuming character generation is fairly quick, and you give the PCs a good reason to explore the tomb.
Level 2: The Upper Tomb
Still linear, but with more branching rooms and some terrain hazards. There is still a clear path "forwards", but the side rooms are tempting. This section is where the lessons of Level 1 are tested and applied. It might take 2 or 3 sessions to explore, and possibly require a trip back to civilization to resupply.
Level 3: The Lower Tomb
There are two main "horizontal" paths and three main "vertical" paths. The dungeon branches and loops. You can reach the surface. You can go deeper. You can end up back where you started. This level is significantly more dangerous than the preceding levels. Dungeon diplomacy and trade also comes into play, as do wandering monsters. You can explore Levels 1 and 2 at your leisure, but if you spend too much time on Level 3 you are taking a grave risk. Level 3 is open-ended. You can add material to extend the dungeon as far as you'd like. By this point, you should be ready to write your own material.
The False Tomb: Represents the joy of discover, the "Oh, I see!" moment, and the thrill of possible treasure. Be sure to praise any player who figures out it's a false tomb. Cleverness should be rewarded. The dungeon also gets weirder and less mundane as you descend. Initially, you're cracking wooden coffins to loot tiny amulets. By the end, you're digging through fungus goblin muck for crowns, trading with a dead snake-man, or hauling treasure chests of gold to the surface.
Describe this area with words like "shoddy" and "chipped" and "damp." It's a root cellar. There are little white roots in the ceiling and gravel on the floor.
The True Tomb: Represents power and unspoken threats. Statues loom. Things shudder in locked coffins. Giant lizards stalk you in the darkness, immortal wizards cut deals, and invincible undead-oozes slither after you.
Describe this area with words like "enormous" and "looming" and "cold". This are is the work of a civilization older, wiser, and crueler than the PCs. The deeper they go, the jumpier they should be.
The Chasm: Represents the unknown, and the wonder of the unknown. There could be anything down there. It could go to the core of the world. There could still be snake-men living untroubled lives in the depths. It's a blank canvas for GMs to add things to this module.
Describe the chasm with words like "bottomless" and "distressing. It's like the entire world just falls away." and "quiet, restless sounds, if you are patient." The PCs should not want to spend any time near the chasm.
The Goblin Warrens: Represents the mirror of the PCs. They live in filth, they respawn and make the same mistakes, they are hungry, foolish, superstitious, murderous, and somehow sympathetic. The warrens are the intrusion of vital and noisy barbarism into cold and moribund civilization.
Describe the warrens with smells and sounds. It stinks. You'll stink if you spend any time in them, and the Tomb of the Serpent Kings doesn't have complimentary baths. Tiny red goblin eyes in the darkness. Chattering teeth and sharp knives.
Getting The Game Started:
Most game books have a section that goes "Here's what a GM is, here's what dice are, and here's an example of play", so I'm not going to write all of that out again.
It's completely fine to introduce the dungeon immediately.
It's also completely fine to say, "For whatever reason, you decide to accept the old man's offer. Every other part of your character's backstory is up to you, but for some reason, you decide to follow the treasure map. What is that reason? Adventure? Debt? Secret cultist orders?"
In my game, the PCs were sent to kill an owlbear. In the course of the fight, the owlbear uncovered the entrance to the tomb.