So You Want to Run OSR: Part 1 - Preparing Your First Dungeon

Last week, I covered the materials you will need for your first session of an OSR game. This week, we'll look at creating your first dungeon.

Per my advice given in "Golden Rule for Sandbox Refereeing," your first session should be spent on a simple dungeon crawl with some interesting adventure hooks that your players can follow up on in subsequent sessions. They will tell you which hook they want to pursue the following session (or if they'd rather just keep exploring the dungeon), and you spend the intervening time preparing it.

I would caution against spending too much time and effort coming up with a "back-story" or "lore" for your dungeon. I understand the urge, but remember that players rarely walk away from a session buzzing about the story you wrote; rather, players love and remember the stories they create. Information about a dungeon can be interesting and fun, and ideally it provides clues to the players about enemies, traps, and treasure that can be found within. For an obvious example, a crypt can be assumed to be full of undead, so clerics in the party would be a boon. Two or three sentences should be enough to give players an idea about the dungeon. Any further information I'd recommend giving to players via NPCs, to encourage interaction, whether this means interrogating factions in the dungeon or rolling for rumors in town.

The amount of rooms you will have to map and key for your first session will depend on how quickly your players explore the dungeon. You don't want to run out of content during a session, but you also don't need to create a 150-room dungeon in a week if your players only explore four or five rooms a session. I'd recommend at least 15 to 20 rooms keyed for your first session. Your dungeon should not be linear, so make sure that even the shortest route through your dungeon has enough content for a session. Gygax recommended keying the first three floors in advance of the first session, in case players wanted to pull a high-risk, high-reward dive to the lower levels.

Don't worry about a beautiful map; your players will probably not see it. Multiple entrances are a plus. Create a few loops and branches, and then connect certain rooms through sub-levels to make an interconnected dungeon. One-way doors and exits that reveal hidden entrances will also make things interesting.

Monsters, traps, treasure, and tricks.

About 1/3 of your rooms will contain monsters. Begin by creating factions (see my guide here). Some factions may be made of multiple kinds of monsters (if goblins and kobolds have an alliance, e.g.), while other factions may even be only one monster (a roaming ogre or a lost mage). Depending on the size of your dungeon, three or four factions per floor is probably sufficient. Some monsters may be unintelligent or otherwise unaffiliated, as well. Decide on each faction's "headquarters," where they gather, where their leader sleeps (and hides treasure!). Per the recommendation in B4, make sure you know what monsters will do should the PCs decide to attack, talk, or wait. REMEMBER TO USE REACTION ROLLS AND CHECK FOR MORALE! Forgetting to do so is a  common mistake new referees make.

In my opinion, it is more fun to interact with a trap you know about than find a trap you didn't know about. I like "Indiana Jones" style traps: it is obvious that there is a trap, but not exactly what it is or how to disarm it. A statuette on a plinth, dried blood on the floor, large cracks in the walls... players can poke around the environment to search for clues. A deceptively simple trap can still pose danger for even experienced players!

Stocking a dungeon can be a bit tricky. Using the treasure tables as given may be fairly "swingy." Think about it this way: players getting 500xp each per session will take 4 sessions to level up. This is a month of play, if you play once a week. Players will "lose" xp by dying or bringing along hirelings, as well. If you have 6 players, they'll have to recover 3,000gp of treasure per session to reach second level in a month. So how much treasure you put in your dungeon will depend on how fast you want your players to level up. Using the recommendations in Moldvay Basic, there is an average of about 255gp of nonmagical treasure per room on the first floor. Going off this, I'd recommend about 510gp per room on the second floor, 765gp per room on the third, and so on. This is on the lower end of what you'd probably want to stock, so don't hesitate to add some more treasure, especially if playing with a large group. Magical items can be rolled for as usual.

For mundane stocking, I'd refer you to Appendix I in the 1e AD&D DMG.

"Trick" is one of the most fun ways to stock your dungeon. Rather than rolling for something, I'd encourage you to truly let your imagination run wild. Don't be afraid to put in something bizarre. I keep a journal handy and write down anything that comes in my head, then pick my favorite ideas from it. Per Moldvay, these should come up about 1/6 times, but I like to keep them somewhat rarer - a few per floor. These also help players orient themselves in the dungeon, because the rooms stick out in their minds.

Some things to keep in mind:

When going for "Gygaxian naturalism," each faction should have a place to eat, sleep, store goods, store weapons and armor, prepare or cultivate food, hide treasure, convene, dispose of waste, quarter soldiers, house their chieftan, & c. I use Dwarf Fortress as inspiration.

Careful mapping should be rewarded. Symmetry and "missing rooms" can indicate where traps and secret doorways are.

Dungeons change! They grow and live. When players come back after time has passed, things should be different. If a character dies in the dungeon and their body is not recovered, it should be scavenged. Your players will be enraged and delighted to find that a goblin has pilfered the late Caliban's axe and is now using it against them. Have a section of your binder dedicated to tracking changes in a dungeon. Which rooms have been explored and must be restocked, what will happen if a faction is allowed to expand, & c.

Finding already-sprung traps and the long-decayed corpses of hapless adventurers can give players valuable information about what to be on the lookout for. A floor full of petrified adventurers is almost sure to contain a basilisk, and a chest surrounded by rotten bodies is best approached with a ten-foot pole.

You may want to put players on a clock, so to speak. This doesn't need to create much more work for you. To discourage the dreaded "five minute workday" where players show up to a dungeon, cast their spells, exhaust their resources, and then return home, for a first dungeon, I like to tell my players that there is a solstice festival in two weeks, and they will be spending their lucre on it. Therefore, all treasure they can acquire in those two weeks can be spent for bonus experience on the solstice day. This gives them a fun and concrete deadline. Of course, the dungeon can continue to be explored after this date, but it helps to use the players' own greed to draw them deeper into the dungeon.

Finally, create a rumor table that indicates features, danger, and traps. This encourages interaction with NPCs in town and factions within the dungeon. I don't like to include wholly false rumors; rather, all my false rumors have a grain of truth to them. The coven of blood-sucking vampires that the Goodman swears to have seen might actually be a swarm of blood-sucking stirges instead. The fearsome cockatrice might be a regular chicken, escaped from a kobold's pen. I like to overplay, rather than underplay danger in my false rumors.

Now you have everything you need to run your first session! I cover the details of running it in the next article, which you can read here.