Generating the Great Hall
The initial area is a crossroads - a junction where each of the 4 halls are 30' wide and go 120' before. After each section, roll to see what the next chunk looks like: 3d10 for Passage, Width, and Pitch; then again for specifics like what kind of side passage or number of chambers
|1||Straight 1d6x60||10||Rise||Left, backward||Base||Citidael||Statue||1d4|
|2||Straight 1d6x60||20||Slight Rise||Left, forward||Base||Temple||Fountain||1d6|
|3||Straight 1d6x60||20||Slight Rise||Left, forward||Base||City||Old Battle||1d6|
|4||Straight 1d6x60||30||Flat||Left, stright||Base||Workshops||Camp||1d8|
|5||60' T||30||Flat||Left, stright||Base||Gardens||Doomguard||2d4|
|6||60' Side||30||Flat||Left, stright||Equal||Tombs||Graffiti Walls||2d4|
|7||60' Y||30||Flat||Right, backward||Equal||Great Chamber||Fortifications||2d6|
|8||60' X||30||Flat||Right, forward||Equal||Tower||Great Pillars||2d6|
|9||Landmark||40||Flat||Right, forward||Left||Fortifications||Magical Residue||3d4|
|10||Chambers||40||Slight Fall||Right, stright||Left||Rubble||Giant Skeleton||3d6|
|11||Ruins||50||Slight Fall||Right, stright||Right||Heavy Rubble||Great Bettle Shells||4d4|
|12||Ruins||60||Fall||Right, stright||Right||Blocked Passage||Ghost Infestation||5d6|
T-Intersection: The passage splits left and right
X-Intersection: The passage continues left, right, and forward.
Y-Intersection: This gets an extra roll for the specific type of intersection. Bottom, Left and Right are in relation to a Y passage where the split 45 degrees from the stem of the Y. Equal indicates a Y intersection, each passage 120 degrees from the next.
Side Passages: This gets an extra roll. Left and right are pretty obvious. Forward and Backward are 45 degree splits based on the direction of travel, straight is a side passage that is perpendicular.
Pitch: Slight rise and slight fall are likely not noticed, rise and fall are obvious to every adventurer. They might be a gradient, some sort of fault like a huge drop or cliff, or grand stairs. Up to the GM because I forgot to add it options to the table.
Landmarks: This gets an extra roll. Big picture stuff -landmarks are tremendous locations that can be used to get one's bearings in the impossibly huge Great Halls. The GM should have some fun and spice these landmark locations. Roll 1d8 again on the Passage table to figure out exits from this feature, or not, whatever.
Ruins: This gets an extra roll. Once great structures that now lie in ruins; like super-destroyed. These are much like landmarks (and are landmarks) but their ruination tends to attract horrible monsters. The GM should double the chance of any creatures that are here of having a lair. Roll 1d8 again on the Passage table to figure out exits from this feature, or not, whatever.
Chambers: This gets an extra roll. Effectively, these are dungeons within the dungeon. The exact size and configuration of the chambers are left up to the GM. If doubles are rolled, there is a second level, triples indicates 3 levels, and so on. Each level uses the same dice to roll for number of rooms, but ignore doubles except from the first roll. The GM can roll 1d8 again on the Passage table to figure out exits from this feature, or not, whatever.