Level 813.1

The Undercroft (or Level 813.1) is a locale commonly believed to be a sublevel of Level 813 due to its drastically differing environment from that which it is connected to.
== Description ==
Existing by all accounts beneath the surface of the Gelid Isle, Level 813.1 is a colossal subterranean expanse of dirt and rock home to countless quantities of refuse, rubble, and scrap. Accessing this locale is only possible by descending into the depths of Level 813 and finding dusty stone corridors, all of which twisting and descending illogically for up to miles on end until opening up upon the landscape that is the Undercroft. Estimations as to the size of this expanse vary, as none have yet found the exact endings of its confines, but many presume it to be easily multiple times the size of the Isle above and at least tens of miles high, with the ceiling of this cavernous location looming so far ahead as to be mistaken for a starless night sky by many.
The environment of Level 813.1 is almost universally bleak and sparse, its terrain composed of powdered dirt strewn across jagged rock and debris forming rolling hills, wide plateaus, strange expansive craters, and mazelike sloped canyons. This barren terrain trends dark and inhospitable throughout its near entirety, the monotony infrequently broken by formations both natural - such as small dripstone oases of ice water ponds and looming stalagmites - and unnatural - heaping wrecks of shattered stone buildings and twisted metal apparati - all of which barely visible in the shadows of the level's peculiar ambient glow, minute yet omnipresent.
Compared to the surface, weather in the Undercroft is much tamer, yet still existent. Calmer temperatures averaging around 40°F permeate the level's entirety, permitting the pooling of dripwater ponds and the flowing of surface rivers through flooded corridors and down to the deep as minute streams few and far between. Precipitation does not come in the form of blizzards and maelstroms, but rather as weightless specks of dirt falling like snow from the quiet shifting of the ceiling above, or raging storms of dust forming colossal walls and slamming through the level. The latter of these weather events is unanimously the result of sudden spikes in force from...
== The Thrum ==
Its presence always felt throughout Level 813.1, the Thrum - as explorers call it - is a ceaseless, echoing, rhythmic boom heard no matter where one is in the Undercroft. Nigh confirmed to originate somewhere beyond the other side of Av Iv (see below), the Thrum is believed to be generated from something mechanical in nature, yet unimaginable in scale. 
For most, the Thrum is a small yet nagging constant in the back of their ears, barely felt as it hammers away in the far distance. As one grows closer to its point of origin, however, its fury grows both audibly and physically, turning from a muffled drum to a wind-stirring thunder. Explorers tell of the waves of force growing strong enough to send belongings flying in a gale, knock people down to their feet, and - at its greatest endurable intensity - launching poor souls tens or even hundreds of feet back through the air only to violently return to the ground. Such more extreme experiences are more often seen during sudden brief surges in the Thrum's intensity - the same surges capable of generating powerful dust storms carried for miles on end. 
Many bold inhabitants or keen-sensed researchers pose that the nature of the Thrum may be far more interwoven with the Undercroft as a whole than we're capable of discerning, as several elements of the level seem almost in-tune with its pulse. Ancient mechanisms condensing air moisture into water pools, battered generators powering the tired lights of old ruins, and many more scattered testaments of machinery somehow still operating all do so in time with the booming about them, pistons roaring and belts racing with each thundering of their aberrant superior. As a result, most aware of this phenomenon believe the source of the Thrum to be some colossal power generator, feeding its energy into ancient devices all across the Undercroft. Until we gain the means to discern the Thrum's source, however, we simply cannot know for certain. 
== The Tomb of Alost ==
Considered nigh-mythological in nature prior to the official discovery of Level 813.1, a common name heard in the histories and folklores of the surface's prime inhabitants, the Penumbras, is that of a nation incalculably old and utterly lost to time: the Kingdom of Alost.
Believed by many penumbras to be the legendary origin of their entire species, details on what the Kingdom of Alost was are juxtaposedly sparse. What little of its identity has survived through stories tells of an empire so mythic in territory and technology that no penumbra nation since dares call itself "kingdom" out of respect, making leaps and bounds in societal advancement and supposedly even establishing settlements across several other levels, a feat most modern penumbras consider inherently perilous. Despite these tales of incredible achievements, all sources and stories tell of Alost inevitably meeting the same fate: a mysterious cataclysm sending the entire kingdom both into a societal and literal freefall, with every last settlement to its name swallowed up by the earth and wiped away without a trace.
With recent history's exploration of the Undercroft, however, these myths and legends are starting to be considered irrefutable fact.
Most who willingly descend into the expanse of Level 813.1 - even ever since its official discovery - take the form of either knowledge-hungry researchers and archaeologists seeking out the mysteries of the thousands upon thousands of ruins strewn across the locale's terrain, or foolhardy fortune-seekers delving into the deep for weeks or even months on end to find lost scraps of valuables, pilfer ancient belongings, and strip down worn-away machinery for expensive metals and components. While these two groups could not be any different in goal from one another, both have come to be known both in the Undercroft and on the surface as "sifters" - individuals bold enough to rush into the dark depths and sift through the veritable tomb of an empire in search of secrets, riches, and glory.
For some, however, that search leads to perhaps the most daunting of the Undercroft's features.
== The Oubliette ==
Found at one extreme of Level 813.1, the Oubliette is a region of terrain where all formations and features give way, replaced across its breadth by an uninterrupted decline descending indefinitely. No ancient structures or geologic interruptions are found in this section of the Undercroft, no dust ever showers down from above or barrels through in tidal waves. Even the Thrum's rhythm cannot be felt or heard upon approaching the lip of this immense descent. 
What few sifters have tried to brave the Oubliette find that as their depth increases in their explorations, the air itself changes in nature. Oxygen grows thin, consistency grows humid, and temperatures fluctuate sadistically between survivable and hypothermic. The silence where once the Thrum dwelt grows deafening, extending its influence to those braving the decline and muffling their speech and footfall. The all-permeating ambient glow of the Undercroft slowly falls away into total blackness that soon swallows up the light of flames and electronics, snuffing out anything granting visibility. 
None have yet discovered what could possibly lie at the bottom of the Oubliette's decline, but that is not to say that none have tried. Scattered across the slope's entirety can be found the wrecks of supply wagons, shells of encampments, and even the withered corpses of those who've tried and failed to brave the descent, the depths where they lay seeming illogically shallow. Many have suggested the decline itself has rejected these remains, slowly pushing them back towards the surface over the course of years. Logbooks of those unfortunate souls found along the descent seem to corroborate this theory, with many claiming to have reached depths far grander than where they lay in finality. 
As for those who've turned back from their endeavors before they met the same end, their stories tell of unintelligible murmurings in the dark, nightmares of lives unlived and beasts unencountered, whispers from diminutive tongues condemning past actions and fostering guilt and sorrow, and - most peculiar of all - the faint melody of birdsong echoing from the bottom of the decline. What could possibly bring about these strange and unwelcoming phenomena, however, will certainly remain unknown until some hardened soul finally braves the Oubliette's depths and returns from the bottom alive. 
== Entities ==
Compared to the Gelid Isle above, Level 813.1's environment is far less encouraging in the development of life in its confines. Much of the sublevel's expanse is devoid of native fauna, and almost no plant life whatsoever can be found across any stretch of the rocky terrain. Yet despite all this, living things can yet still be found in the Undercroft, sparse in number and strange in development yet present nonetheless.Most of the Undercroft's ecosystem centers entirely around the existence of natural vents scattered across the sublevel, appearing as small volcano-like rock mounds producing ample amounts of chemical vapors that cloud around their source for up to miles in diameter. While the gases generated by these vents is nothing more than strange-tasting fog for humans and most other lifeforms, it is incredibly beneficial for the primary lifeform found in the Undercroft: a species of stilt-legged, cat-like creatures roughly the size of small deer known as Fumelurkers. These skittish entities subsist almost entirely on the vapors of the gas vents they live around, gaining incredible amounts of energy from its consumption. Some researchers believe they process these gasses so efficiently, even, that the overabundance of energy from individual meals resulted in their evolution into jumpy and quick organisms solely in order to burn off excess nutrition.
Fumelurkers are in turn the main source of nutrition for the Undercroft's far more distinguished inhabitants, the Eschek-toi. An intelligent species of cyclopean humanoid entity with lower bodies comparable to arachnids, the eschek-toi are a universally nomadic group known for their incredible speed of movement and their immense familiarity with the Undercroft. Their societies are organized into wandering clans who mostly scavenge the ruins found across the sublevel for tools and materials, many hunting or even herding fumelurkers between gas vents for sustenance while others have switched to trading salvage and services to sifters in exchange for surface goods and food such as glapreseed. Their cultural and technological development is considered by most human researchers to still be in its early stages, on-par with the societies of Earth's iron age, and the total population of eschek-toi in the Undercroft is believed to be somewhere a little under 100,000.
Last but not least among the inhabitants of the Undercroft is a group who's perhaps called it home for longer than any others, despite their total detachment from the sublevel's ecology. Found all across the terrain of Level 813.1 - particularly in its countless ruins - is a group of penumbras so altered from their surface cousins as to nearly be considered a sub-species, known as Penumbra Wraiths. These ancient individuals clad in tattered clothes and rusted cybernetics are noted as being incredibly zombie-like in appearance, and are believed by most to somehow be all that remains of the inhabitants of the mythic lost kingdom of Alost, left stranded in the Undercroft for unknown millennia. Many of those that sifters have encountered stand unmoving and unresponsive, stuck in a dormant state of nigh-death that they cannot be woken from, while those still awake and mobile are either incapable of speech or incapable of reason, all viewing sifters and local fauna with unending hostility and attacking those they encounter on sight.
== Bases, Communities, and Outposts ==
Compared to the immense population of the Gelid Isle above, Level 813.1's inhabitants are unsurprisingly sparse. Most non-native individuals who willingly venture into the depths of this sublevel do so to become a sifter, seeking knowledge of things long forgotten or seeking fortune in the pilfering of ruins and scrapping of old machines and valuables. As such, while plenty of temporary encampments and horrendously minute settlements can be found sparsely scattered across the Undercroft, only three communities are of any worth to note:
=== Dún Dubhach ===
* Fortified settlement situated at the opening of an entry corridor near the surface city of Dún Emne.
* Home to a permanent population of roughly 3,200 humans, penumbras, and eschek-toi, while easily hosting an additional 1-2 thousand temporary inhabitants at any given time.
* Mostly consists of rickety buildings and towers of timber, encircled almost entirely by a wooden palisade.
* Seen as a hub of activity to sifters, most of which using the town as a launch point for expeditions and salvage runs all across the Undercroft.
* Acts as a trade center of the sublevel, feeding wealth from the exploits of many sifters and eschek-toi clans back up to Dún Emne who in turn supplies the town with food reserves and military forces.
=== Bleak ===
* Hub site for dozens of eschek-toi clans, technically considered a settlement due to its constant use.
* Arguably has no permanent population, but often sees hundreds to thousands of temporary inhabitants at any given time, usually averaging out at 1,500.
* Consists of a massive canyon site whose ridges are lined by the walls of an old ruin, at the bottom of which flows a small stream carried down from the surface by a flooded entry corridor.
* Seen as a semi-sacred hub of trade and politics for the eschek-toi clans, who meet here constantly to trade scavenged goods or settle disputes between groups.
* Safety of visitors to this site is uncertain as not all eschek-toi clans are welcoming of sifter activity in the Undercroft. Safest to avoid traveling here.
=== Av Iv ===
* Largest ancient site in the entirety of the Undercroft, stretching out for miles in territory.
* Inhabited solely by penumbra wraiths, the exact population of which believed to rest somewhere around 40,000.
* Consists of a colossal city of ancient buildings and fortifications believed to have once housed hundreds of thousands of penumbras at its peak, those few left of its population fiercely defending it from any who they see within the city or on its periphery.
* Named after the supposed capital of the lost kingdom of Alost by sifters, who often risk venturing into the city in search of valuables and historical artifacts.
* Situated just before the point of the Undercroft where the intensity of the Thrum is capable of injuring explorers.
* Travel here is heavily discouraged, even if well-equipped and well-prepared.
== Entrances and Exits ==
Both entry and exit into Level 813.1 is believed to be only possible via the navigation of ancient stone corridors found in the earth and rock of Level 813. Such passages can be found all across the Gelid Isle, either hidden in the depths of cave systems, set into rocky outcroppings tucked away behind foliage, along the weathered and dangerous passes of the Eterfol Mountains, or with their entrances utterly buried beneath the dirt and rock of some unassuming patch of terrain. As it stands, no other means of entering or exiting the Undercroft has been found outside of these passageways.
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Category:Levels
Category:Sub-Levels
Category:The Gelid Isle