D&D 5E Advice on How to Run a Megadungeon Game

[Fanaelialae]

Explaining why "just send an army" isn't the answer something I want to include. If it is important, in 5e the power of a 100 person squad of grunts makes a 4th level party look like a joke. So why not armies? Why the PCs?

IMO, the explanation for this one is easy. Dungeons are naturally restricted spaces, greatly limiting the strength a large force can bring to bear. Having 100 men is of little benefit if you have to fight the ogre 1v1 because it is holding a natural choke point. It's not a good plan unless your strategem is to throw wave upon wave of your men until your enemies are buried by the endless corpses.

 

[NotAYakk]

IMO, the explanation for this one is easy. Dungeons are naturally restricted spaces, greatly limiting the strength a large force can bring to bear. Having 100 men is of little benefit if you have to fight the ogre 1v1 because it is holding a natural choke point. It's not a good plan unless your strategem is to throw wave upon wave of your men until your enemies are buried by the endless corpses.

In a realistic situation where the dungeon was of military importance, you'd have supply lines, flanks, scouts, siege engines. Scouts would avoid actually fighting and flee on contact.

Castkes (or other equivalent) bastions. Engineers who seal passages to optimize topology, or break through walls to crack bottlenecks.

A heavy SWAT team to handle an ogre guarding a narrow approach would not be the same as a scouting force. The scouting force is expendible and non-combatant; the heavy SWAT expensive and combat focused.

Now, this is also related to the similar surface problem of "why use PCs instead of a knight, squire and 50 peasant leavies". Often the answer is "the PCs are there and the knight+leavies isn't, or is busy". But with a megadungeon, it stays where it is, and is either important or not.

Don't get me wrong, there are plenty of ways to justify it. I'm just saying justify it.