Large Dungeon

The Large Dungeon is a rare feature added by GregTech 6. It is a procedural underground structure that is primarily made out of decorative GregTech stone blocks and has some lights, therefore almost no hostile mobs can spawn in it. "They are more of a Showcase of Usage thing for GT6."[]

The structure can generate centered on a grid  + 4 chunks apart (default 176 blocks), but not within 256 of either the x or z axis, and only on the overworld. It will not generate if that center point does not have bedrock under it (i.e. skyblock void worlds). It will be made of a primary and a secondary stone type selected from the twelve GT6 varieties, plus some Concrete and carpet of a single random color.

Components
Every Large Dungeon is guaranteed to have exactly one entrance tower and one barracks somewhere. Sizes vary, and may not have any other rooms at all but average four others. Corridors connect all groups of rooms to a central point. Empty rooms are about as common as the Workshop and Library are.

Entrance Tower
Two very shallow staircases spiral around a straight drop in a "Mario Pipe" tower that extends a short way above ground from the dungeon. Concrete arches mark each exit from this chamber.

Barracks
Each of the four corners of this room is walled off as a separate private carpeted bedroom. Each has a button & pressure plate iron door, a Bed, a Wooden Bookshelf, a Crafting Table with a Porcelain Cup on it, and a Key Locked Safe full of loot. One of the 'books' visible on the bookshelf is actually the Key for the safe (there are four different keys here). The cup often has a drink in it.

Corridors
Some T-junction corridors have a nook in them, containing a crafting table, a dyed Porcelain Cup (often filled with drink), two piles of Coins, and a Brass Chest or Reinforced Wooden Chest with stronghold corridor loot. Coin piles spawn in copper, silver, gold, and platinum with platinum coins being rare and copper common. There is also a rare chance of a coin pile being empty and not spawning.

Workshop
Arguably the richest room in the dungeon, the workshop looks like an empty room, but has things in each corner.

The NW storage corner has a Steel Mechanical Safe full of jungle pyramid loot that will bind to whichever player opens it first. Under that is a Stainless Steel Compartment Drawer containing various components in Stainless Steel, Bronze, Invar, and Brass. The Advanced Crafting Table has a similar set of Steel parts in its top inventory, a single Lighter in its underslung inventory, and a Ceramic Measuring Pot on top. Two Mass Storages contain a large amount of the stones used to build the structure, in their cobblestone variant. Atop them is a Stainless Steel Bookshelf containing eight core training manuals, some village blacksmith loot books, and maybe a Key (possibly on the hidden back side, possibly a fifth key that doesn't open anything). There is also a vanilla crafting table with a Mortar on it in the corner between three Stainless Steel Chests containing some mineshaft corridor, stronghold crossing, and dungeon loot. And a Steel Barometer Gas Cylinder full of Propane. Nearly everything in this corner is painted the same color as the concrete.

The NE forge corner has a Vanilla Anvil, a Grindstone, and an Anvil in Black Steel, Red Steel, Blue Steel, or Vanadiumsteel. There is a ready-to-use Burning Box (Solid) under a Smelting Crucible with two random Molds beside it, all made of Bronze, Invar, or Steel. In the corner is a Stainless Steel Chest with village blacksmith loot.

The SE washing corner has a Drum full of water with a Funnel and two Taps, all in stainless steel. Under one Tap is a partly filled Cauldron (Vanilla), the other a Mixing Bowl Table. A Bathing Pot Table stands nearby.

The SW corner probably has some Wooden or Ironwood Barrels full of drinks, and / or Propane filled red dyed Steel Barometer Gas Cylinders or Helium filled yellow dyed Stainless Steel Barometer Gas Cylinders.

Library
This room has wall to wall Carpet and two stories of bookshelves in the corners populated with random loot that can go in a Wooden Bookshelf, replacing all others with vanilla Books. There might be one of the five Keys somewhere on these shelves.

In front of the corner shelves are a Jukebox, Enchanting Table, Ender Chest, and a crafting table with a stretched Night Vision Potion in a Porcelain Cup on it, in some order.

The wall sections have three versions, depending if Thaumcraft 4 and / or Mystcraft are installed. Normally, there are two more bookshelves with stronghold library loot in them, an stretched Night Vision potion in a Porcelain Cup, and two Flower Pots that might get substituted with a ZPM.

With Thaumcraft, they are Tables with colored Tallow Candles and maybe Coin piles on them instead of Flower Pots or ZPM.

With Mystcraft, the first side is an Ink Mixer, a Mixing Bowl Table with some ink in it, a Book Binder, a Writing Desk, one bookshelf of loot with a Lectern on it. The other sides have two Bookstands and four bookshelves of loot with Lecterns on them.

Pool
A two block deep pool of water lined with Concrete fills the center of this room. It is one of the better-lit rooms due to the Glowtus on it, and is large enough to fish in. This room only generates when it will have exactly two entrances.

Storage Vault
This room has a Concrete piston door sealing its only entrance. Each of the four corners might have a pile of Crates and Partial Crates of ingots, dust, or plates of Iron, Steel, Stainless Steel, Copper, Tin, or Damascus Steel. The three sides might each have a pile of Barrels of Creosote Oil, Seed Oil, Lubricant, Glue, Latex, Holy Water, or Purple Drink and / or Drums of Oil; occasional Propane and Helium Barometer Gas Cylinders occur here too. Finding this room nearly empty is not uncommon.

Portals
These rooms also have a Concrete piston vault door, and only occur with a single entrance, but are each unique in the structure. The End portal is already active (and in the floor where it is easy to accidentally walk into), the other three are frames waiting for activation. Except for the End Portal room, they always have a chest with the portal activation item, the Hunting Guide for that dimension, and a bit of related loot in it. The Twilight and Mystcraft rooms only generate if those mods are loaded.

Configuration Details
Several properties of Large Dungeons are configurable by the server, by editing in the section: overworld { structure { dungeon { large { B:Enabled_true= I:MaxSize_7= I:MaxY_20= I:MinSize_3= I:MinY_20= B:PortalEnd_true= B:PortalMyst_true= B:PortalNether_true= B:PortalTwilight_true= I:Probability_100= I:RoomChance_6= B:ZPMs_true= }  }  } As is normal for GregoriusT, the portion between the "_" and the "=" is the default value, but is also part of the configuration name and must not be changed. Both  and   are denominators - a "one in x" chance. The size and y-level of the structure are chosen evenly from their ranges.

The size of the structure refers to the edge length, in chunks, of the area in which rooms can spawn. After the entrance and barracks are randomly positioned, every chunk has a chance to become a random room. Increasing  will allow for dungeons with many more rooms, and force the spawn points further apart.

If  is set high enough, or the overworld generates low enough, two additional features occur. The Corridor roofs are replaced with Glow Glass of the color at every point they can see the sky, including underwater. Pillars of primary stone will extend below each room and corridor down to a surface (or the void) below.