This is the history. I am working on the other details. I am creating the location, and hopefully a scenario for it.
History of Twisix
Note: This history of Twisix is accurate although incomplete. Much of this information is unknown to the Imperium, and any known information is secret, forbidden, lost, or all three. Information which can be found in the Imperium is more often inaccurate legends than the truth.
Pre-History
The comet Twisix was formed with the Shlafshrei solar system billions of years ago. It is a massive comet, the size of a small moon. The rock in Twisix is radioactive and its heat melted the ice around it, so the heavy pieces gradually sank through the ice to the core. There a solid radioactive mass remains, surrounded by a sea of boiling water. The steam forces its way into cracks in the ice, creating underground steam vents and geysers. Icequakes shake and crack the comet, but in the frigid dark of space the steam refreezes and the cracks refill with ice.
In the inner sea, or in the slush surrounding chunks of radioactive ore, life developed in the form of bacteria. The bacteria spread slowly through the ice, carried by steam eruptions and spread through slow but inexorable growth. Although existing in absolute darkness, a billion years later would light would shine upon it the bacteria was revealed as red in color, like a bloody stain in the ice.
Xenos
At some time an unknown Xenos race discovered the comet. They bio-engineered a species that could tunnel beneath the ice and feed on the bacteria, the excava wurms. Why they did this is as much a mystery as who they were. To keep the species from mutating due to the radiation, they built in a mutagen which repaired the species genes continuously. The species was successful in surviving whether or not it ever achieved the xenos’ goal.
Human History
Humanity discovered the comet in the expedition of rogue trader Jasta Aubenhelm, who was exploring and trading in the Calixis Sector in the decades leading up to the Angevin Crusade. In his reports to the, he simply noted a large comet containing radioactive ore in the Shlafshrei system and named it Twisix.
In the aftermath of the crusade, Rogue trader Jukan Remor knew of the comet from Jasta’s report and decided to attempt to mine the radioactive ore, figuring it would be cheaper to drill ore out of ice than a rocky planet. Imperial guard units were demobilized and settled on planets as feudal warriors to tie the worlds to the Imperium and provide a loyal militia. Remor hired as many retiring hellbore tunneler crews as he could, twenty-three, and requisitioned their hellbores as well.
He established an outpost on the surface of Twisix, inhabited by the service crews and camp followers of the hellbore units. The tunnelers drilled into the ice. They discovered that the radiation prevented communication with units within the ice. The extreme cold and inexplicable presence of steam vents caused tunnels to refill with ice within weeks. Seven tunnelers were lost.
The ore near the surface is widely scattered and could not be mined on a profitable scale. The tunnelers probed ever deeper. Tunnelling several kilometers into the ice, they discovered the tunnels of the excava wurms. The radioactive crystals, dubbed “dragon pearls” by Jukan as a marketing measure, were discovered and attempts to mine ore were abandoned in the quest to find more crystals.
Jukan expanded his operations. The re-icing of tunnels was prevented with hotboxes – iron boxes containing radioactive ore. The camp followers were moved into the tunnels and rewarded for each dragon pearl found. The hellbores were scattered around the comet to increase the area being prospected.
After months of operations, Jukan left the comet in the command of a trusted underling. Jukan himself headed out into the Halo Stars and disappeared from history. For years the prospecting was good and the colonies within the ice grew as additional prospectors and pleasure girls were imported. A fungus was found which would grow in the irradiated tunnels, and a breed of goat that would eat the fungus. The population of the colony became self-sustaining and the food nearly so – if you were willing to eat goat or fungus.
It did not take long for mutations to being to appear. The hellbore crews quarantined themselves inside their vehicles to avoid the radiation and became their own mini-colonies. Strangely the mutations tended to take a few specific forms. The mutants swelled in size, grew tails, and became more flexible. They became smaller imitations of the excava wurms – the xenos mutagen to keep the wurms’ genes free of mutation controlled the direction of the human mutations.
The wurms came less often near the surface, perhaps avoiding the heated tunnels. And so dragon pearls became harder to find. Two hellbores descended into the depths to explore, neither was heard from again. With the decline in the pearl trade, the trade ships came less often. Six centuries ago, the regular trade of dragon pearls ended and they became a legend to most of the galaxy.
Men searched the lower ice tunnels searching for pearls. Many disappeared. Over time on Twisix, legends grew of mutant cities in the deep tunnels. Mutant humans in the form of the wurms, with cities littered with dragon pearls. It was said that the mutants were cannibals, and only the most desperate or daring ventured below.
Four centuries ago, one of the few dragon pearl smugglers decided that the secret comet was a perfect base for pirates. He organized a small fleet which raided the shipping between Dreah and Siren’s Den. They traded the stolen foodstuffs to the inhabitants of Twisix at astronomical prices for the dragon pearls. The pirate raids were investigated by Inquisitor Vanist McCann who tracked them to Twisix. He did not land, and simply bombed the comet from space, destroying the remains of the surface outposts. Over time the ice healed.
Fifty years later another pirate fleet operated out of Twisix. Again it preyed on the shipping between Dreah and Siren’s Den. Again Inquisitor Vanist tracked it down. A force of guardsmen landed and guncutters were sent down into a hellbore tunnel. Communication was lost immediately. An imperial force was sent into the comet but did not return. Vanist had the comet bombed from space for two weeks. It had no effect on the tunnels below and again the ice re-healed when he left.
When the underworld found out about the failed Imperial raid on Twisix, it became a haven for those hiding from the law. The existence and particularly the location of the comet remained a secret, but those with enough money and desperation found there way there. Piracy continued but on a smaller scale. Smuggling became more common as wealthy outlaws could afford to pay for luxurious goods to be brought in.
A century ago the pirate fleet came to Inquisitor Vanist’s notice once again. He had been mind wiped since the last raid, and repeated the same actions. Another imperial force disappeared into the comet and weeks of bombardment shattered the uninhabited surface.
Current
Officially there has been no word of Twisix for a century. Dragon pearls are legends even to the rich, and the truth of the legends is known only to a handful of the wealthiest. Criminals speak of Twisix as a lost paradise for outlaws. Its real existence is known only to some smugglers and pirates, and few of them know where it is. Bounty hunters speak of it as a paradise for their ilk, where there are endless rich bounties.
On Twisix itself, life has settled into a gloomy and violent existence. The strong prey on the weak, and the mutants in the dark prey on them all. They are each dependent on each other, and dependent upon the radiation which keeps their tunnels clear, and grows their food, while it corrupts their bodies and souls. A refuge for heretics, a forgotten outpost of xenos, Twisix is a dark and secret ulcer within the Imperium.