Base Chance of a Dungeon in a Hex
Each hex has a 1 in 10 chance of having a dungeon inside. Once a hex has terrain and fillings then it is simple to add a dungeon by using the existing structures within as the basis for a dungeon. If there is a ruined structure within the hex, then one can simply select one of them as leading into a dungeon. If there are no abandoned structures than one of the existing structures may be selected to having been built over a dungeon. The same could be done for existing natural landmarks or monster lairs within a hex. In this manner, hex fillings can be used as inspiration or procedural generation for the dungeon within. Four examples are given below, each drawing from a hex crawl (of 37 hexes roughly matching the expected number of dungeons) previously made.
(7,8) Swamp Hex with Ruined ChurchThe dungeon here could be the crypts of the church now submerged and half filled by the swamps. The church may have used an existing structure for its foundation and now that foundation is deep under the swamp. I imagien this dungeon has a level of the church, a level of the crypt half submerged by the mire, a level underneath untouched by the swamps largely empty, a level deeper still which has not been opened for a great period of time.
This dungeon strikes me as the hidden barrow of the figure shown by the idol. Perhaps he was an ancient warrior of great renown and was interred with his slaves and treasure. Perhaps the slaves have risen as wraiths who would curse at those who seek to plunder his tomb.
(5,10) Forest Hex with Great Stone Idol
(6,5) Plains Hex with Rock formation of a large cliff and numerous holes all along it each of differing size but most the diameter of a man.As I have recently been reminded of Junji Ito's The Enigma of Amigara Fault I would have the dungeon be similar to it. Hidden nearby is entry to a complex where once human figures have been stretched out to near impossible proportions.
(7,12) Waters hex with Harassed by Ghosts, Lunatic Sailors, and a Giant BirdIn my notes I had that those lunatic sailors are cultists who sacrifice victims to the Massive Bird and their victims are now risen ghosts. This dungeon builds itself conceptually as a complex on a cliff at the top of which a giant bird comes to roost in order to eat sacrificial victims.
Dungeons Near a Settlement
For each random NPC encountered I use the following table to determine their alignment.
NPC Alignment Table
There is a 1 in 6 chance of a NPC having a chaotic alignment and in doing so is likely to betray the characters or manipulate them into serving them. This same probability can be used to determine dungeons near a settlement. Villages roll a 1d6, Towns roll a 1d6+2, and Cities roll a 1d6+4 on the following table below. Like above three examples are given below, drawing from the same previously mentioned hex crawl.
Nearby Settlement Dungeon Table
|1-5||No Nearby Dungeon|
|6-7||Dungeon in the same hex|
|8||As above and Dungeon 1 hex away*|
|9||As above and Dungeon 2 hexes away*|
|10||As above and a Dungeon 3 hexes away*|
*Placement can be determined by the image below.
(6,5) Village of Gramling (Roll of 6 on the Nearby Settlement Dungeon Table)While there is already an existing dungeon in this hex, I feel that the addition of another dungeon would not congest it too greatly. There is a ruined village in this hex as well and I could see that the ruin of it may have come from a dungeon below it completely unrelated to the gaping cliffs. Perhaps a great evil was trapped in the earth below and then one day a random youth from the village explored the inside and disturbed it allow it to spill outwards. This is where I would place Fungal Growths on Prison Walls.
There are two dungeons here. This hex is largely absent of fillings, mainly roads and the town itself, so the dungeon within this hex may have nothing to with the actual town. However, one my rumor table I have it that "A cadet from New Rind found a silver sword, which he claims fell down from the moon". SO perhaps there was once a cult dedicated to the moonfolk and they have a temple on a hilltop which can be only be seen and entered on the night of a full moon. The other dungeon is in hex (3,4) which contains a ruined mine. Perhaps the reason the mine was shut down because it entered a cavern complex full of some foul subterranean thing which now haunts the mine.
(2,5) Town of New Rind (Roll of 8 on the Nearby Settlement Dungeon Table)
Now we have three dungeons in proximity. The first is in the actual hex itself, and in my notes there is a dungeon below the castle where the Jarl has been locked away to hide his curse. That solve the question of that dungeon.
(8,11) City of Hringepi (Roll of 9 on the Nearby Settlement Dungeon Table)
The next dungeon is in hex (7,10) contains an old faith temple. Like the church in hex (7,8) perhaps it was built on an existing structure which is sealed away. I have no issue with reusing this idea of building on top of existing constructs. Perhaps it was sealed off due to the numerous traps and false reliquaries much like a pyramid.
The last dungeon is in hex (8,7) contains a ruined estate as well as a large camp of tribal horsemen (nomads). Off the top of my head the nomads consider it a cursed place and have placed a trio of riders nearby to monitor it. They will approach those who wander close and warn them of certain doom. I would say that the estate was the site of a Jarl's exiled son who was banished for his obsession with the occult. He became an accomplished magic user and after a failed conjuration his estate is filled with malicious magics, magical reagents, monsters, and a grotesque mockery of him.