Thurstle Island: City of the Ancients

The metallic ink just doesn't translate on screen.

The City of the Ancients is Thurstle Island's mega-dungeon. A glaciated urban husk, long abandoned by it's starborne builders. Like an iceberg, the portion visible above the surface is merely a fraction of the whole. 

This is largely inspired by John Arendt's Black City and H.P. Lovecraft's At the Mountain's of Madness (full text). It will also borrow lots of elements from the new edition of Deep Carbon Observatory (incredible, buy immediately) and Roadside Picnic. 

Unlike Cove Town or the Old Forest, I'm not ready to nail down all the specifics yet. I have the skeleton and plan to flesh it out while the players begin their exploration. They'll probably start with one the mini-dungeons (like this or this) anyhow. 

That said, I want to think aloud as I put it together.

Nodes are significant buildings.

How it Works

Structurally, the City is one big, interconnected dungeon. The towers connect to a labyrinthine underground complex that descends deep into the planet and ultimately connects to the Underdark.

• I've drawn a loose point-crawl to connect keyed locations. This will certainly evolve.
• The top layer of the under-dungeon is a transit layer that connects the cardinal zones of the city (drawn in highlighter on the point-crawl sketch)
• Zones define the borders of various encounter tables (in light dashed pencil, you can see where these borders could change).
• Towers will be small to medium sized dungeons. I've started drafting them. A few may get their own posts.  Some will only be unlocked later in the campaign.

• The meta-structure of the under-dungeon is sketched on the pink post-it at the top of this post.
• The interiors of the city (drawn by Nihei) are swarming with oozes, jellies and the haywire servitors of the City's creators. The Creators and their goop tech will get their own posts.

Selections from my Pinterest

The Surface

The city is buried in a broken glacier. Moving across it is very difficult. 

• Dozens of dark towers pierce up through the ice. Most of them are inaccessible.
• The city is much, much colder than the rest of the island. 
• Under the snow, there are many frozen corpses.
• Harald Halfjaw's meaner, younger brother, Kjartan, has established a semi-permanent camp on the edge of the City. It'll get it's own post eventually. 

The Cold

When traveling across the City's surface:

• Everyone takes a level of deprivation until they are able to get warm.

Into the Odd blended w/ 5e exhaustion

• For each leg of travel, everyone must make a saving throw vs CON or gain another level of deprivation. 
• Heavy fur coats or other cold-weather gear grant advantage on these saving throws.
• Time around a fire and a mug of hot tea will remove all deprivation from cold.

Hazards 

1. Roc - An enormous raptor nests atop a tower deep within the city. It circles high above the island and swoops down on prey caught without cover. Moving across open spaces is suicide. 
2. Weather - Violent thunder blizzards come up suddenly and unexpectedly and can make surface travel across the city impossible. Some blame the druids.
3. Rival Adventurers - The PCs will not be the only ones pillaging these ancient ruins. Outside of town there are no laws and the only recourse for violence is blood feud.
4. Local Trouble - I have overlaid zones for various groups (white apes, berserkers, cultists, ice snakes, otherworldly interlopers etc.) and will populate encounter tables accordingly. 

Bumble, stats as bugbear.