Ostrakan

Ostrakan is a Forge/Fortress world, the only moon of the blue gas giant, a 6th planet in the Europas solar system, which is located at the edge of Garon Nebulae, Segmentum Tempestus. Ostrakan serves as a base for the local Adeptus Mechanicus forces and as an impregnable fortress world, the last bastion of resistance for the Federation, that will resist all but the Exterminatus-grade weaponry, as the surface is nothing but a frozen wasteland, and all life happens hundreds of meters under, in vast cavern systems. It was colonized under the initiative of the Europan Planetary Federation, after the secession from the Imperium of Man.

031.M41 to 231.M41
Ostrakan was the last planet to be colonized in the Europa system at the initiative of the Adeptus Mechanicus, who wanted to push the boundaries even further. After the initial examination and analysis of the cave system, massive work-gangs, servitor legions, and huge construction and drilling machines were put to work, creating foundations for urban development and backbone infrastructure.

232.M41 to 664.M41
With the foundations and infrastructure completed, first sectors were inhabited, first with workers and later with people who immigrated from other worlds. The government had to encourage people to move, so families were given homes or other real-estates for free or got significant monetary compensation. As the workers and construction machines kept working, more and more sectors were urbanized and the wheels of the local economy started revolving.

665.M41 to 861.M41
During those years, Ostrakan was hit several times by strong, unexpected earthquakes that cause catastrophic damage to many sectors and killed hundreds of thousands of people, either directly by massive cave-ins or indirectly by damaging water pipes that caused floodings, misdirecting lava rivers into inhabited zones or causing a release of toxic industrial chemicals. The cause why it happened was never fully explained, as simulations of tectonic plates didn't match any calculations. Some higher-ups brought up the thought of possible Genestealer infestation and the approaching hive-fleet, but widespread gene-screening and mandatory medical check-ups showed no results to support this possibility. Subtle precautions were made, however.

862.M41 to 991.M41
At 989.M41, a massive blackout occurred that blew fuses across half of the planet. It was never publically explained what actually happened, but damages were hastily repaired. The true reason could be tracked into the Σ-39 sector, where local tech-priests managed to lit a webway portal, that was stolen from the space hulk many centuries ago. Since then, the Skitarii forces roam, map and explore the local webway network. Nobody but the highest Magii are not aware of anything.

992.M41 to current day
There isn't much going on here, apart from the way of the hectic life that is common in heavily industrialized worlds. New caverns and tunnels are still being bored out and urbanized, although, on a much lower rate, as new districts are not in high demand. Many sectors are thus hollowed out, but remained completely empty. And a subject of many rumors and scary legends of alien monsters and murderous madmen.

Landscape & Nature

 * The surface is inhabitable despite the air being somewhat breathable. Due to the distance from the sun, the surface temperature is constantly around 230K and the constant freezing wind makes survival and movement difficult even with protective gear. Luckily, apart from a handful of camouflaged outposts, armored gates, and air ventilators, there is nothing there.
 * Dozens and hundreds of meters below, there is a massive cave system that, to some extent, reaches around the entire planet. The caves range from narrow tunnels to halls hundreds of meters wide. Since the planet is still volcanically active, albeit not as much as it was before, inside the caves is a relatively pleasant temperature. This also causes some issues with volcanic gases being released, so thorough air filtration was deemed necessary.
 * Apart from lava rivers and lakes flowing through some parts of the cavern system, there are water rivers as well, but with the millennia-long exposure to the volcanic gases, it is not safe to drink. It has to be cleaned and purified first. And with sewage and wastewater often being dumped into the lava fields, rain can often occur in some sectors.
 * There was no native fauna and flora due to the lack of sunlight and general isolation, but colonists brought over some livestock and with help of artificial sunlight, even farming is possible to some extent, but not enough to be completely self-sufficient.

Population, Society & Culture

 * With all population living in the caves, that are divided into hundreds of sectors, the majority of them are divided by thick, air-tight blast doors, majority of people spend their lives on only a handful of them. Not that free travel is outlawed, but people have little reason to, as a single residence sector contains all necessary facilities to live, from grocery stores to entertainment or healthcare.
 * As the sectors are divided into categories by their focus, residence sectors and industrial sectors are most frequent. Residence sectors are usually relatively quiet, with cleaner air and efforts to make them look visually pleasing. Industrial sectors are where the industry of all types is, from mining sites through foundries to automated production lines of fine electronics. It's usually dirty, hot, greasy, smelly and noisy, with the main focus on logistics accessibility and industrial performance, not on workers comfort. Other sectors are restricted sectors, usually an Adeptus Mechanicus or military installation, logistics sectors serving as vast cargo hubs for loading and unloading thousands of tons of materiel (also known as starports, as most logistics sectors focus on loading and unloading goods into starships), agricultural sectors for growing the few crops that can be grown here, utility sectors that have water purification plants or air filters, and leisure sectors, dedicated to entertainment.
 * Commuting between sectors is usually orchestrated by high-capacity trains running between sectors, transporting both goods, supplies or workers.
 * Since Ostrakan is also a fortress world, every single inhabitant is required to undergo basic military training, to learn how to handle a weapon. In case of invasion, everyone is required to report at their designated posts and defend their homes. Sectors were projected with this in mind and bunkers, forts, hideout, watchtowers, and strongpoints are built at the critical locations. Sectors can be hermetically sealed to cut-off the enemy forces and some can be flooded too, either by water or even molten lava if the situation is deemed desperate enough to further aid with delaying or defeating the enemy.

Notable locations

 * Gate 14 - The biggest and strongest armored gate, carved into a mountain, spacious enough to swallow a Cobra-class destroyer. It is used very rarely, though, and usually for a cargo ship.


 * Brig sector - An industrial sector containing foundries and forges large enough to build a starship. Connected with Gate 14.


 * Sector Σ-39 - A tightly guarded restricted sector ran by the Adeptus Mechanicus. Rumors are that members of extremely secretive Xenarite sect operate inside.


 * Garean Heights sector - Considered as the nicest residence sector on whole Ostrakan. It is a large cave with slowly-graduating, mesa-like hill with an actual forest growing there, while the houses are below the cliffs.


 * Flemwell Isle - A small residence sector hosting a small conglomeration of houses on an island surrounded by lava fields.

Notable people

 * Archmagos Lucilius Alva Draken - The highest-ranking Tech-priest in the Federation. On his behalf, Ostrakan abandoned the binding dogma of Cult Mechanicus and began inventing and improving, instead of just preserving technology. He would be executed as a Heretek, if the Martian Tech-priests ever found his whereabouts, thus he contributes to the isolationist politics of the Europan government.
 * Vikenti Mencher von Aggelern - The largest industrial tycoon. He specializes in electronics and consumer goods production and is one of the largest employers on the planet.