Chasm Forge was built on top of an asteroid from which it mined resources. The station itself was circular and made up of several sections connected together by circular rings. The station was connected to the asteroid by a single central support column. Conveyors were used to mine the asteroid. The station housed a smartsuit repair bay, central nuclear core and dormitories. (TV: Oxygen)
Chasm Forge originally housed a crew of forty. Upon the Doctor's arrival, only four life signs remained. These were those of Tasker, Abby, Dahh-Ren and Ivan. Ivan's wife Ellie was also part of the crew, although she died prior. (TV: Oxygen)
Chasm Forge was designed as a mining station powered by a central nuclear reactor. Its computers were controlled by an onboard artificial intelligence called Velma. She monitored communications, the airlocks, the oxygen supply, the smartsuits and had many other functions.
The smartsuits on board Chasm Forge possessed mechanized exo-skeletons that meant they could take control and function automatically, without there necesarily being an occupant present. When put a user the exo-skeleton would wrap itself around the user's limbs and the rest of the suit would teleport onto the occupant. The suit formed an invisible force field around the user's head to provide them with oxygen. However, these shields were not strong enough to endure the vacuum of space. Collapsible helmets were thus provided along with the suit to remedy this. Magnetic soles were built into the heals of the suits' boots to allow them to walk on the outside of the station. The suits were equipped with a number of tools such as welding lasers to perform various maintenance tasks. Each suit was connected to the onboard AI and could receive remote commands. If ordered to, the suits could "deactivate their organic components". This meant killing the occupant by emitting a lethal electric shock that fried the person's nervous system.
Chasm Forge was built on top of an asteroid in order to mine copper ore by Ganymede Systems, a spacefaring organization. At had a crew of forty workers, each equipped with a Ganymede Systems Series 12 smartsuit, and an onboard AI.
After several months, the crew became less and less productive and the station was declared non-profitable. The Ganymede Systems board of directors thus sent the AI an instruction to "deactivate the organic component" of the smartsuits. This meant killing the crew, as they were deemed to expensive to live.
All but five smartsuits received the instruction and the crew were promptly killed until only crew members Ivan, Tasker, Abby, Ellie and Dahh-Ren were left alive. They were spared as their suits were off-network when the command was sent.
In an attempt to transmit a distress call, Ivan and his wife Ellie ventured outside in order to hook up their suits' radio to an antennae. They were unsuccessful and as they made their way back inside, Ellie was ambushed by two smartsuits that ripped her helmet off, exposing her to the vacuum of space and killing her. Though Ivan was horrified, he managed to get back inside and barricaded himself in a section with the remaining crew.
The Twelfth Doctor, Bill Potts and Nardole picked up the distress call and landed the TARDIS on board Chasm Forge, only to be quickly forced to don smartsuits as there was no oxygen except inside the suits. They were chased by the smartsuits and eventually made their way to the remaining crew.
Hoping to get back to the TARDIS to evacuate the survivors, they were forced to go outside the station. Tasker and Dahh-Ren were killed along the way. But due to Bill's suit malfunctioning, the Doctor was forced to give her his helmet and was exposed to the vacuum of space, blinding him.
After Bill was seemingly killed by the smartsuits, the Doctor, Nardole, Ivan and Abby went to the station's nuclear reactor core and hooked up their vital signs to it, rigging it to blow if they were to die.
Upon hearing this, the onboard AI calculated that Ganymede Systems would make the biggest loss ever and deemed the survivors more expensive dead than alive. They were thus spared and the Doctor revealed Bill was in fact alive as her suit did not have enough power to lethally shock her.
Following these events, the Doctor transported Ivan and Abby back to Ganymede Systems' headquarters in order to inform the public. Six months later, a successful revolution took place and the company was permanently shut down. (TV: Oxygen)
In the Shadow World, a virtual reality designed by the Monks to be a perfect copy of the Doctor's universe, simulacra of the Twelfth Doctor, Bill Potts and Nardole had recently returned from Chasm Forge. The Doctor had been blinded as a result of his trip there. (TV: Extremis)