Underdeck

Star vessels, star fortresses, and surface habitats often contain various empty and forgotten places that have simply been abandoned.

The underdeck refers to the lower levels or hidden areas of those conglomerations of STC technology. These areas are often less populated or empty and can be used for various purposes, such as storage, maintenance, or housing hidden facilities.

Maintenance Tunnel: These tunnels and ducts are pathways or corridors providing the access to critical maintenance areas. They are typically used only by servitors and constantly monitored by servo-skulls.

Lost Space: Lost Space refers to unused or forgotten areas between different components of a star vessel or a habitat. These spaces might have been left unutilized during construction or later modifications. In space, these places are often exposed to the hard vacuum and freezing temperatures as an area is not covered by the life sustainer.

Rat Road: They are hidden, narrow, and tight passageways or routes that can only be used by ratlings seeking to navigate unnoticed through the complex Imperial architecture.

Sewer: These tunnels and conduits exist within larger star vessels or habitats to handle waste disposal and drainage. They are usually unhealthy, grim and neglected areas, often serving as hiding places or secret routes for certain individuals.

Hive Foundation: A hive city refers to a gargantuan city created by the combination of numerous hive towers. The hive foundation represents the lowest and often overlooked levels of a hive city. Many hive cities have histories spanning over 10 millennia and beyond, and the foundations of those cities rest on previous crumbled and collapsed hive towers. Those are dark and dangerous places, refuge for destitute citizens, hiding mutants, and individuals seeking to be forgotten.

Restricted Space: Restricted spaces are areas within that are off-limits to regular inhabitants or visitors. They usually contain classified information, valuable resources, hazardous environments, or dangerous entities that require strict access control. Most often Imperial authorities, Inquisition, enforcers, ecclesiarchy, etc, have placed on the restriction. Reasons behind restrictions are sometimes lost for these places, and they are guarded for an eternity just to keep up with the ancient dictations and traditions.

Forgotten Space: It refers to component areas that have been completely abandoned, fallen into disrepair, or lost to time within a star vessel, space station, or habitat. These areas might hold remnants of past inhabitants or hidden dangers.

Under-market: The under-market represents an illicit or black market that operates clandestinely within the hidden depths of a star vessel, star fortress, or habitat. It is a place where illegal or exotic goods, services, and activities take place away from prying eyes. They are usually hard to find without a prior introduction or a local guide.

Aqua Reservoir: These are large storage areas within larger star vessels, star fortresses, or habitats that hold water supplies for various purposes. An underground water reservoir supplying a hive city can be up to dozens of cubic kilometers in size, and the old ones may even have developed their own ecosystems. Water reservoirs may have hidden or forgotten sections, providing potential hiding places or secret routes.

Toxic Dump: These are designated areas within transport vessels, industrial star fortresses, or habitats where hazardous or toxic materials are stored or disposed of. The dumps can become forgotten or abandoned, posing significant risks to future generations who venture into them. One with a good quality re-breather and a sealed hazmat suit can travel there with only minor hindrance.

Irradiated Area: Locations within the drives of star vessels or cores of star fortresses and habitats that produce high levels of radiation, pose significant risks to anyone entering those areas. Only those blessed by protective garments of the Omnissiah or those unhindered by the fear of radiation sickness and mutation dare to wander these places.

Depleted Mine: These are abandoned mining sites within asteroids, moons, or planets where the resources have been extracted, often leaving behind derelict tunnels and dangerously corroded infrastructure.

Abandoned Pneumatic Rail: These are unused or forgotten pneumatic rail systems within large star vessels, space stations, or habitats. They were once used for fast transportation but are now in disrepair and left in disuse.

Obsolete Elevator: These are outdated and no longer functional elevator systems that have fallen into disuse. They potentially conceal hidden areas or serve as eerie reminders of the past. Some of them, even in a ruined state, still demand proper authorization to function.