Thallium Refining Colony TC-AE265

TC-AE265 is an Aryx modular habitat in the Outer Regions of The Abyss. ThalCorp Industries (TCI) operates the base as a Thallium-203 mining colony.  
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It is the main location for the Into the Abyss adventure.

Purpose and Founding

Thallium-204 (T204) is vital to most high-tech electronics manufacture and while there is some of it in the world, The Cataclysm made finding it exceptionally difficult, not to mention dangerous. When the first T203 deposits were found by Abyss prospectors, a gold rush started to find rich deposits that could be exploited.   TCI is by far the largest and most successful supplier of T204 thanks to its numerous mining colonies in the Abyss. Most of the refined material is supplied to their owner, ThalCorp Enterprises, but any excess is sold to other intressents.   TC-AE265 is the most remote registered colony in the Abyss, located in the Outer Region almost 4 000 kilometers away, taking over 60 hours to reach at regular cruise speed (35 knots). TCI prospected the site approximately 16 months ago and had the Aryx habitat built on site 11 months ago. In spite of its short operating time, TC-AE265 has already reached an output equal to three of the top producing colonies of TCI. It is an extremely profitable base for TCI.  

Design and crew

TCI built TC-AE265 for extracting and refining T203 into T204. To fulfill this purpose, it needs a crew of 65 to operate the mining equipment. In addition to this there is need for maintenance crews, engineers, service personnel, administrative staff and nuclear technicians. The base’s life supports can handle up to 300 people and with all the crew needed, and select families, there are just about 300 people living on the base.  

Construction and Value

TCI knew well before construction that TC-AE265 would be a ludicrously profitable venture. After initial prospecting the Probe Site was built to find the richest pockets and determine exact placement of the Mining Site.   Including prospecting and probing, the cost of construction for the entire habitat landed around 660 million credits of which most was transportation and construction crew salaries. Experienced divers capable of working welders and submarine construction work are expensive. The modules were transported using Nixie submarines and assembled on site.


17th Millir, 117 PC

Orbital, Station
Approximately 300
Location under
Owning Organization
Related Plots
Thallium-203 extraction
Thallium-204 refining


To fulfill its purpose as a mining base it has several modules built and connected to it to allow the base to function at peak performance and handle any emergency that can occur.
  Every modules is directly connected to its neighbor, with only a small corridor separating some modules from others due to necessity. The Moonpool is placed off of a cliff side to allow clearance for entering submarines.   The whole base covers and area of 600 by 1400 meters, not counting the Service Umbilical and the Nuclear Powerplant. The NPP is placed approximately two kilometers from the base, connected via the umbilical. This is to protect the base in the case of a meltdown and allow crew to evacuate the base.  

Relationship with TCI

Ægir Gjalladoðr was appointed as on site chief administrator of TC-AE265. Ægir had significant experience with supervision and management, previously having worked as management chief for the TCE research division. Initially, things were sour between TC-AE265 and TCI upper management as Ægir had significant changes in mind for crew rotations and deliveries that upper management did not agree with. Eventually, TCI came around to Ægir's changes and TC-AE265 became TCI's most profitable outpost in the Abyss.  

The Incident

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On the 15th of Millir the base came under attack by a local wildlife native to the rocky substrate, named Skirrka. They entered the base through Probe Site, which they rapidly converted into a hive entrance. Administration was attacked first, killing anyone in charge immediately. Security was lax and unprepared for an attack, so when the Skirrka melted their way through the doors between Recreations and Administration, they rapidly turned Recreations into a mass slaughter.   With no one in charge, the automated systems went into auto-shutdown to prevent a nuclear meltdown. The surviving crew were either found by roaming Skirrka or died of hypothermia after the heat system turned off and the base went subzero.   ThalCorp Industries sent an emergency team to find out what happened, following an automated service message sent by the base. The team found the base in shutdown and eventually uncovered the Skirrka invasion. Fearing that the creatures were intelligent enough to make use of the base equipment, Senior Nuclear Technician Brok Borgo set the reactors into manual overload and the team fled the base, narrowly escaping death at the hands of the Skirrka.  
Into the Abyss
Plot | Feb 24, 2021

A horror one-shot adventure set in the submarine refining colony of TC-AE 265.

A playthrough of the above adventure can be seen here.

Articles under Thallium Refining Colony TC-AE265

Building / Landmark | Jan 21, 2021

"The Suit Chute" is the main administrative wing of a mining base. It houses the mainframe server room and offices for all the administrative staff.

Building / Landmark | Jan 21, 2021

Decontamination is the main medical and science facility of a mining base. It is always built as an interface between the "dirty" and "clean" sides of the base, separating the engineering and mining section from the living areas.

Building / Landmark | Jan 21, 2021

Engineering is the mechanical maintenance workshop and main airlock for a mining base.

Building / Landmark | Jan 21, 2021

The hab houses all the workers on the station in a compact apartment complex.

Mining Site
Building / Landmark | Jan 21, 2021

Sunken into the substrate of the floating island, the mining site is the primary extraction and processing facility of the mining base.

Building / Landmark | Jan 21, 2021

The moonpool is the main entrance and exit of the mining base for submarines. The open pool allows submarines to enter the base and for the crew to disembark in the atmosphere without using an airlock.

Nuclear Powerplant
Building / Landmark | Jan 21, 2021

The nuclear power plant houses two NPP-2160 nuclear reactors and provide power and heat to the base.

Probe Site
Building / Landmark | Jan 21, 2021

The probe site, initial site for prospecting, now converted to a communications array.

Pump Station
Building / Landmark | Jan 21, 2021

The pump station house the water filtration that provides clean drinking water for the base, as well as the pumps for circulating reactor coolant.

Building / Landmark | Jan 21, 2021

Recreations is a combination of leisure area, arboretum, sports and shopping area where off-duty crew and their families can wind down.


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8 May, 2019 01:16

And here I was reading and thinking, golly this sure would make a disturbing horror setting. Nothing like a deep sea, remote location to have a massive mess of disgusting slaughters! And lo and behold!   Seriously though, great entry into the competition, I like the use of article blocks to help fan out the article and the base itself.

Check out my worldbuilding in the Ethnis Universe!
8 May, 2019 09:51

I actually ended up running this adventure with Guy (from How to be a Great GM) and some friends of mine. It was a blast. ^^ Thanks for the read, Barron!

Author of prize-winning RPG settings Dark Shadows and Cinders of the Cataclysm. Designer of the narratively focused Celenia D10 RPG System.
Elias Redclaw
7 Jun, 2019 13:09

Holy heck. That last part was scary. And I mean really really scary. Just having to imagine being there in the deep dark ocean with no one that can hear you and then suddenly being attacked by monsters from your nightmares is terrifying. Fantastic job tobs! The horror element is strong with this one! Some other things I could compliment upon though is the the technical details of the base. As a guy who absolutely loves details, you managed to show the functions and structure of the base in a clean and organic way, something which I myself particularly struggle at. One last thing I should compliment though is the use of block links to give the reader info about the various modules of the base.   A question I had though, was that has the ThalCorp Infustries ever tried to make another large base like this? Preferably with more security? Or were they scared shitless after the incident or didn’t have the resources to build another base? I’d say that this was yet another example of an amazing horror article from you. Congrats yet again tobs and keep up the damned good work!

7 Jun, 2019 15:02

The TC-AE265 incident is very recent. There's not been much time for ThalCorp to really change their routines. Although they do now have extensive xenobiologist and geologist presence during prospecting in order to prevent this again.

Author of prize-winning RPG settings Dark Shadows and Cinders of the Cataclysm. Designer of the narratively focused Celenia D10 RPG System.
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