Megadungeon DM Overview

As I have said before, running a megadungeon is fundamentally different than running other types of campaigns. As such, it must be approached differently than a city adventure or a story driven location campaign. Let's look at how best to facilitate the megadungeon in play.

1. Choose a system that works best for the environment. 

• Combat needs to be quick (you may have 7-8 in a 4 hour session). In a modern game, this can be difficult. Don't let players debate during combat. They should have a plan before swords are swung. At first, keep them aware they must move quickly, and by session 3, impose a turn time limit (1 minute?)
  In OSR games, the rules facilitate the quick movement of combat. Still, letting them make a detailed plan while monsters are attacking with halitosis breath may not be the best time. Keep them moving.
• Using a skill system needs to be handled with care. If you use a game with a robust skill system, bonuses should be given for good description: "I search for traps" should be a Investigation check with no bonuses, while "I lead the party slowly ahead, rolling ball bearings down the hallway then prodding for pit traps with the 10 ft. pole." should garner a +2 or better bonus to the roll. Always give good description a reward. The players quickly realize the description matters.
• Healing needs to be a resource. Giving all HP back for resting makes it difficult to pressure the players to leave the dungeon. In a modern game, I would change the mechanic to 2x level HP are healed upon long rest.
• XP should always be used for leveling. Milestone XP does not work because it removes player agency. It should be feasible for the party to reach levels 3-4 on the first floor of the dungeon (even if it is slightly boring). This should be feasible on any level. Milestone leveling also squashes exploration. Why go exploring when there is not a reward? (Also, if playing 5E find the 3.5 XP tables and use those for your characters).
• Know how to handle Save or Die. In modern games, this is problematic because character creation is a time consuming process. Instead, use a system like Exhaustion in the modern games. But, hit them hard with it. Make them feel the repercussions of that failed save. (Also, have them make 2 characters at session 0, so another is ready to go).
• I DM best in OSR style games: Swords & Wizardry, OSE, BECMI and the like. Knowing where my strength is, I most often choose these. Familiarity is important to keep a game moving, and you should be able to adjudicate quickly. Don't jump into running a megadungeon in a game that you are unfamiliar with. 

2. Understand how megadungeons work mechanically. They use some tropes over and over again.

• Exploration is the primary motivation within a megadungeon, and the DM must find ways to motivate the group forward. This could be treasure, a kidnapped NPC, a rival or enemy drawing them forward. Maybe an NPC needs a rare alchemical component from deep within the dungeon to make a cure for the king? Use mcguffins often, but make almost none of them

  

  The Great
  Winged Gargoyle
  (Barrowmaze)

  necessary.
• Factions are the RP areas of the megadungeon. Often factions are at odds with each other, and the PCs need to choose which one they help. This is probably a lesser of two evils scenario. Let the PCs choose, though.
• Combat (as mentioned before) needs to be quick. It is noisy and attracts other denizens to grab whatever is weakened (or dead). Keep it moving. Make sure the group knows that more dangers are watching and ready to pounce on the weak.
• Traps are often deadly. Save or Die is common in megadungeons. 
• Riddles and puzzles are fun side-bars. They should be noticeable, but not stopping advancement. (The Great Winged Gargoyle in Barrowmaze is a great example of a puzzle that works well). Reward the solutions!

3. Keep the dungeon fresh. If the players think they are just slogging from corridor to corridor and combat to combat, they will get bored quickly.

• Factions break this up well. Make the NPCs more interesting than NPCs in town. The NPCs in the dungeon have esoteric goals. They are (probably) strange and alien to the group. 
• Rival adventuring parties can add a pressure to find the mcguffin. Use them to motivate and frustrate the group.
• Vary combats. Make some rooms have 2-3 (or more) levels to approach and attack. Have skeletons bust out of a wall in the middle of another combat. Make sure wandering monsters show up (and maybe even attack the creatures the PCs are fighting). Have falling walls or debris. Don't let combat be static.
• Make sure that the group has access to puzzles and riddles. Finding a solution to one of these could be the serotonin dump to keep them motivated. It also gets them to backtrack and discover missed areas.
• Design levels to be thematically and visually different. A huge cavern of mushrooms with shadows moving just outside of the torchlight is an interesting change to the claustrophobic quarters that led there. Adding a lake makes for interesting choices: cross? find water breathing and explore underneath? Avoid? 

Megadungeons are an art form, and can be painted with any medium. I prefer the OSR brush, but there are a lot of people out there who use the 5E paint set successfully. Even with the differences, we all enjoy stabbing the monsters in the darkness.

Are you enjoying this series? Is there a topic you want me to cover? Let me know, either here in the comments or on Facebook.