Note: here's another foundational, toolbox type post as I build out Trade Town, the island of Thule, and the Black City for sandbox type play before posting any of the dungeons.
The city is full of rubble, ice and snow, and every hex is difficult terrain, except for the colonnaded processional boulevard that provides a clear road through the city. Most groups follow the dirt track from Trade Town and begin exploring the city near the Well of Woe, hex A. All results assume this is summer exploration, when the median temperature is a balmy 38° F or so (3-4° Celsius).
For each hex the group enters, there's a chance to discover a major feature - roll on the table below. Major features can be encountered just by traversing the hex; if a group performs a detailed search, make a roll on the minor feature table to see if something unusual has been discovered. It takes 8 hours to search a hex.
As mentioned in the wandering monster post, the city is loosely divided into 4 zones - zone 1 is the southern end of the city near the Well of Woe - those areas closest to Trade Town and most picked over by previous explorers are Zone 1. Zone 2 is below the Great Glacier. Zone 3 is everything north of the Glacier. (I still may put together a simple map color coding the zones for easy visual reference). When rolling for both major or minor hex features, add 0 for Zone 1, +1 for Zone 2, and add +2 for Zone 3 on the tables. Crossing the Great Glacier will have it's own post.
The focus of exploring the Black City will be the set locations (the areas with letters on the map) and the extensive dungeons beneath the city; that being said, I wanted an approach to generating hex contents on the fly for groups that choose to wander the ruins. I reviewed the excellent Lesserton and Mor a few months ago and loved the ideas presented in it for generating detailed random city hexes - this is a heavily simplified approach but should work fine for groups moving from point A to B through the city. I'd also reward groups 100-200 bonus xp per each hex searched.
Major Features (roll d10 with modifiers)
Minor Features (roll d10 with modifiers)
3 Battle Site
Modifiers to Major and Minor Features rolls:
0 for zone 1, +1 for zone 2, +2 for zone 3
A quick note on monsters:
Many of the monsters were discussed in the notes on the wandering monster post; berserkers have their own bestiary article; a few other monster will have their own bestiary articles.
An excavation is a site where a previous group started clearing rubble, ice and snow, or digging into a collapsed building, looking for artifacts. There's a 25% it's an active site (use Traders for the encounter stats).
The party has found a building with one or more accessible floors. There are 6 basic building geomorphs (on the way). Roll another 1d6 for number of floors (1-2, ground floor only; 3-4, 1st and 2nd floor; 5-6, ground floor and basement). A building is a lair 25% of the time, otherwise roll once on the Minor Features table.
The hex contains a monster lair. Recommended choices (d8): Giant Shrew, Giant Furry Snake, Ape-Men, Ghouls, Berserker Stage 2, Berserker Stage 3, Wight, Bandits (zone 1 or 2 only) or Star Demon (zone 3).
A previous group has stashed some gear here; it's either buried or hidden (50% each) and will contain rations, equipment/ weapons, or an unguarded treasure.
The group finds a location used as a campsite by someone else. There's a 50% it's defensible (surrounded by walls, on a hill or high ground, or similar set up) and a 25% chance of a water source nearby (and a further 25% chance the water is tainted with roid worms). There's a 1-in-6 chance some Veterans will be returning to claim their site.
A group of dead raiders; they've been killed by weapons or monsters (50% of each).
Some humans have set up an ambush site - equal chances it's berserkers, bandits or an NPC party.
(A random table of artifacts is coming soon…)
Common hazards include collapsing rubble, ground, or a pit. Hazards can be detected by dwarves and thieves. Collapsing rubble is triggered on a 1-2 unless detected; 2d6 damage to a random party member as they tumble down a slope or get caught in a rock fall. Collapsing rubble drops an unfortunate down 10-30' (treat like any other covered pit trap). An open pit is also 10-30' deep. There is a 25% chance any 30' drop connects to a narrow sewer tunnel that leads to a Transit Tunnel.
The group stumbles into a monster's ambush site or hunting ground; something is hiding in wait 50% of the time, and if so, the monsters surprise on a 1-3. Recommended choices: Giant Shrew, Giant Furry Snake, Ape-Men, Ghouls, Berserker Stage 2, Berserker Stage 3.
The ancient Greys died in a mass extinction event that left permanent scars across the city; roll on the table below. If a zone is indicated, it will be 120' in diameter.
1 Haunted zone
2 Empowered magic zone
3 Psychic trauma
4 Dispel magic zone
6 Radiation hazard zone
Nighttime encounter with disturbing images of spectral aliens or poltergeists; sense of uneasiness during the day.
Zone randomly fluctuates between doubling range, duration, or effect of a spell.
"As if thousands of voices suddenly cried out in terror and were suddenly silenced". All die rolls in the area are -2 due to distractions from the lingering psychic screams tainting this area.
Anti Magic Zone
This powerful field suppresses magic; it turns off magic items and has a 25% chance of permanently destroying potions. Items return to normal after they leave the zone (ruined potions stay ruined).
Supernatural and Weird Science
A zone with an unusual supernatural effect - examples include low gravity, heavily magnetized stones that attract weapons, unquenchable fires that burn cold, a zone that anyone who enters falls asleep, levitating rubble, a zone that negates all sound, a portal in mid-air that leads into the ethereal plane, a zone where a disembodied astral spirit possesses a character, and so on.
A scarred crater where characters take 1hp /turn in the zone (save vs poison to negate).