Colony ship (World Enough and Time)

A Mondasian colony ship was travelling from Mondas to pick up some colonists. When the ship almost traversed into a black hole, the crew experienced the effects of time dilation, causing time on the higher levels of the ship to slow down in comparison to the lower floors, to the point that a thousand years passed on Floor 1056, the lowest floor, in the space of less than two and a half days on the flight deck.

When a team of engineers found themselves trapped on the bottom floor, they were forced to spent the rest of their lives down there; a thousand years after settling on Floor 1056, a huge city had formed and begun to degrade after centuries of occupation by the ship's engines. To survive, the residents evolved into Mondasian Cybermen, (TV: World Enough and Time) and after – who had crashed his TARDIS on Floor 1056 some years prior –  lost control of them, they spent centuries evolving themselves into more advanced forms, determined to convert the entire ship and complete the final stage of their original mission: Operation Exodus. (TV: The Doctor Falls)

Layout
The ship was approximately 400 miles long and around 100 miles wide.

Decks
The ship contained over a thousand decks, each of which presented a Mondasian environment. These included:
 * 0000 - The main control deck. (TV: World Enough and Time)
 * 0502 - A deck containing a solar farm. (TV: The Doctor Falls)
 * 0507 - A deck containing the largest of the ship's solar farms. (TV: World Enough and Time) The locals here were saved from the Cybermen by the Twelfth Doctor, Bill and Nardole, although the floor was reduced to an incinerated wasteland as a result. (TV: The Doctor Falls)
 * 0508 - An agricultural deck, designed to automatically produce food for the floor's population, as well as those of the nearby floors, such as Floor 0507. Sometime after being abandoned,, and Alit prevented a Cybermat attack from some CyberNeomorphs. (PROSE: Alit in Underland)
 * 0900 - A city deck. The Cybermen flew through this floor on their way to Floor 0507. (TV: The Doctor Falls)
 * 1056 - An urban deck, containing various apartment blocks and a hospital. (TV: World Enough and Time) Eventually turned into a Cyber-factory. (TV: The Doctor Falls)
 * Other floors mentioned on the lift scanner are: 1052, 1051, 1050, 1049, 1048, 1047, 1046, 1045, 1044, 1043, 1042, 1041, 1040, 1039, 1038, 1037, 1036, 1035, 1034, 1033, 1032, 1031, 1030, 1029, 1028, 1027, 1026, 1025, 1024, 1023, 1022, 1021, 1020, 1019, 1018, 1017, 1016, 1015, 0951, 0950, 0949, 0948, 0947, 0946, 0945, 0944, 0943, 0942, 0941, 0940, 0939, 0938, 0937, 0936, 0935, 0934, 0933, 0932, 0931, 0930, 0929, 0928, 0927, 0926, 0925, 0924, 0923, 0922, 0921, 0920, 0919, 0918, 0917, 0916, 0915, 0914, 0913, 0912, 0911, 0910, 0909, 0908, 0907, 0906, 0905, 0904, 0903, 0902, 0901, 0899, 0898, 0897, 0896, 0895, 0894, 0893, 0892, 0891, 0890, 0889, 0888, 0887, 0886, 0885, 0884, 0737, 0736, 0735, 0734, 0733, 0732, 0731, 0730, 0729, 0728, 0727, 0726, 0725, 0724, 0723, 0722, 0721, 0720, 0719, 0718, 0717, 0716, 0715, 0714, 0713, 0712, 1711, 0710, 0709, 0708, 0707, 0706, 0705, 0704, 0703, 0702, 0701, 0700, 0699, 0698, 0697, 0696, 0695, 0694, 0693, 0692, 0691, 0690, 0689, 0688, 0687, 0686, 0685, 0684, 0683, 0682, 0681, 0680, 0679, 0668, 0667, 0666, 0665, 0664, 0663, 0662, 0661, 0660, 0659, 0658, 0657, 0656, 0655, 0654, 0653, 0652, 0651, 0650, 0649, 0648, 0647, 0646, 0645, 0644, 0643, 0493, 0492, 0491, 0490, 0489, 0488, 0487, 0486, 0485, 0484, 0483, 0482, 0481, 0480, 0479, 0478, 0477, 0476, 0475, 0474, 0473, 0472, 0031, 0030, 0029, 0028, 0027, 0010, 0009, 0008 and 0007. (TV: World Enough and Time)
 * Other floors mentioned on the lift level indicator at Floor 0000 are: 0995, 0994, 0993, 0992, 0991, 0990, 0989, 0988, 0987, 0986, 0985, 0984, 0983, 0982, 0981, 0980, 0979, 0978, 0977, 0976, 0975, 0974, 0973, 0972, 0971, 0970, 0969, 0968, 0967, 0966, 0965, 0964, 0963, 0962, 0961, 0960, 0959, 0958, 0957, 0956, 0955, 0954, 0953, 0952, 0363, 0362, 0361, 0360, 0359, 0358, 0357, 0356, 0355, 0354, 0353, 0352, 0351, 0350, 0349, 0348, 0347, 0048, 0047, 0046, 0045, 0044, 0043, 0027, 0026, 0025, 0024, 0006, 0002 and 0001. (TV: World Enough and Time)
 * Further floors mentioned on the lift level indicator at floor 0507 are: 0797, 0796, 0795, 0794, 0793, 0793, 0792, 0791, 0790, 0789, 0788, 0787, 0786, 0785, 0784, 0783, 0782, 0781, 0780, 0779, 0778, 0777, 0776, 0775, 0774, 0773, 0772, 0771, 0770, 0769, 0768, 0767, 0766, 0765, 0764, 0763, 0762, 0761, 0760, 0759, 0758, 0757, 0756, 0755, 0754, 0753, 0752, 0751, 0750, 0749, 0748, 0747, 0746, 0745, 0744, 0743, 0742, 0741, 0740, 0739, 0738, and 0509. (TV: The Doctor Falls)
 * Although she did not specify any floor numbers, Alit stated that there were laboratory levels. (PROSE: Alit in Underland)

Each level from the bottom and up would move a little slower than the one below it, due to the time differential, from proximity to the black hole. (TV: World Enough and Time, The Doctor Falls)

Crew
At take off, there were fifty crew members aboard the ship. They included at least twenty engineers, the chief engineer Franq, the Captain (PROSE: Jorj), and Jorj, the janitor, (TV: World Enough and Time) and the man responsible for checking for stowaways prior to the ship's launch from Mondas. (PROSE: Jorj) Following the effects of the time dilation from the black hole, the bottom floor became filled with generations of lifeforms, each descended from the ship's crew, in a huge city. The hospital on this floor became the genesis point for a race of Cybermen. (TV: World Enough and Time) A colony of farmers and children lived on Floor 0507, although following the Cybermen's attack, they were evacuated by Nardole and Hazran to Floor 0502. (TV: The Doctor Falls) A team of farmers were also based on Floor 0508, although their whereabouts following the rise of the Cybermen on Floor 1056 was unknown. (PROSE: Alit in Underland)

Technology
The ship was fitted with super-fast inertia lifts and was propelled by rear thrusters. Aboard the lowest decks, evolution of technology was advanced. In order to adapt to expiring environments, an artificial evolution was devised. The Mondasian inhabitants were gradually upgraded into Cybermen. (TV: World Enough and Time)

The black hole
Sometime after the apes of Mondas had evolved into the human Mondasians, the colony ship was launched from Mondas to pick up some colonists, with a skeleton crew of fifty, including the Captain, chief engineer Franq and Jorj, the janitor and only non-human. On day 43 of its voyage, it was drawn into the gravity well of a black hole. After the Captain berated Jorj for not alerting him of the black hole sooner, a team of twenty engineers, including Franq, were sent from Floor 0000, the flight deck, to Floor 1056, the lowest level, to reverse the rear thrusters and escape the black hole. However, time dilation caused by the black hole's gravity resulted in time passing much more slowly on the higher floors on the ship in comparison to the lower floors, as the higher floors were closer to the black hole.

The deterioration of Floor 1056
As a result, the team at the bottom of the ship found that, after reversing the rear thrusters, they were unable to return to Floor 0000. Forced to spend the rest of their lives on Floor 1056, they established a huge civilisation that their descendants inherited over several centuries, but over time, the city degraded significantly as the bottom of the ship aged dramatically, whereas the higher floors, in particular Floor 0000, did not. At some point,, after being banished from Gallifrey, landed on Floor 1056; he attempted to escape the black hole but flew his TARDIS too fast, burning out the dematerialisation circuit and stranding him on the colony ship. The Master then "killed a lot of people, took over the city", and "lived like a king" before the people of Floor 1056 tired of his cruelty and overthrew him. The Master was forced into hiding as "Mr. Razor", the caretaker of the city's hospital.

Operation Exodus
By this time, conditions on Floor 1056 had grown inhospitable to the point that the hospital began Operation Exodus, an operation with the intent of transforming the people of the city into cyborgs to dramatically extend their life spans, so that they could not only survive on Floor 1056, but also survive the journey to Floor 0000 to take command of the ship. However, following the manipulation of Razor, the cyborgs that were produced from Operation Exodus were a race of Cybermen that the Master intended to use to conquer the galaxy. The "patients", an early form of Mondasian Cybermen, were converted from humans by the hospital's surgeon in the conversion theatre, although they were insufficient as a final solution to Operation Exodus as they were in constant pain from the conversion process. Although a temporary solution was found in the development of voice synthesisers that allowed the patients to be muted, a permanent remedy to the problem was needed, and thus the patients continued to evolve over the years.

Whilst the patients were used to escort people from the city to be converted in the hospital, they were also sent to the higher decks to capture any other humans for conversion. One team of patients were sent to Floor 0507, but were attacked by the farmers, who shot them down at night and chained them to crucifixes in the fields during the day. However, at night, the patients sometimes broke free and resumed their original mission, forcing the farmers to constantly fight them off.

Bill's new life
On Floor 0000, the day after Franq and the original twenty engineers were sent to Floor 1056, Jorj detected hundreds of life readings at the bottom of the ship. The Captain sent another team to Floor 1056 to deal with the "stowaways”, but when the lifts returned, a patrol of patients arrived, capturing the remaining humans and taking them back to Floor 1056, leaving Jorj behind due to him being non-human. By the next day, Jorj had broadcast a distress signal; in response, the Twelfth Doctor's TARDIS arrived, and, Bill Potts and Nardole emerged. Initially monitoring the trio from inside the TARDIS, the Twelfth Doctor quickly emerged when Jorj arrived and threatened to shoot them, after Bill's human life-signs were detected by the hospital on Floor 1056, who, in response, sent a team of patients in the lifts to capture her. When the lifts arrived, Jorj shot Bill despite the Doctor's efforts to stop him, and the patients took her back to Floor 1056. The Doctor left a message in Bill's subconscious to "wait for [him]", and after explaining the effects of the time dilation on the ship to Jorj, proceeded to knock the janitor out before he travelled with Missy and Nardole in a lift to Floor 1056, stating that he'd never be able to fly the TARDIS properly in close proximity to the black hole. (TV: World Enough and Time)

On Floor 0507, there resided a group of farmers who possessed rifles. They were faced by the prototypes that had travelled to their floor from 1056. They spent the night shooting them down, then stringing them up on wooden crosses during the day. They were plagued by these "cyber scarecrows" (as one child called them) for an unknown amount of time - they had left floor 1056 for several hundred from their perspective. One day, a shuttle raft blasted through the floor, containing the Doctor, a cyber converted Bill Potts, the Master, Missy and Nardole. With the Doctor injured, Nardole rallied the town over the coming weeks to prepare for a Cyberman invasion; the prototypes were merely the advance guard. As such, the siege of floor 0507 began. Nardole hacked the floor to ignite certain fuel lines around the floor to fool the Cybermen their technology was a threat to the Cybermen. Floor 507 was ultimately destroyed by the Doctor along with most of the Cybermen. Nardole moved the townspeople to floor 502 where there was another solar farm and they would be safe for years until the surviving Cybermen could regroup and find them.

During the siege of floor 507, Missy provided the Master with a new dematerialisation circuit for his TARDIS, allowing him to depart the colony ship. However, before he left, Missy forced a regeneration upon the Master and the Master killed Missy with his laser screwdriver.

The Doctor also stayed behind on floor 507 to delay the invading Cybermen while Nardole evacuated the townspeople, using the sonic screwdriver to detonate more fuel lines until he was eventually shot down by the Cybermen, beginning his own regeneration. Before the process could take hold, he used the sonic screwdriver to detonate the entire floor, destroying the majority of the Cybermen though some still survived on the lower levels of the ship. (TV: The Doctor Falls)

After the Doctor's departure, Nardole – still aboard the colony ship – remained in contact with Bill via space-time telegraph. During this time he continued to fight the Cybermen on an almost daily basis. (WC: The Best of Days)

Nardole lived for hundreds of years following the battle, as leader of the Solar Farmers, and was ultimately able to defeat all the Cybermen, until all they had to deal with were "Cybermats every spring". (PROSE: Twice Upon a Time)

Nave colonial (World Enough and Time)