Kadavan

Kadavan is the homeworld of the Avikan. It is a harsh desert planet. It was abandoned in a mass exodus after the Theleans invaded it nine times.

Geography
Avikan homeworld is Kadavan, an arid world with little surface water but high amounts of subsurface water in the form of underground lakes and rivers. The Avikan lived mostly in oases, mountain cities, some underground cities too, often extracting water from deep below the ground. The subsurface water was far too deep to actually live at such depths, but it could be pumped up in the right places. At daytime, Kadavan was a hot desert, but at night it grew very cold too (sometimes below freezing temperature). The Avikan generally took shelter at night, but they could survive colder temperatures for some time if needed.

Sandy deserts are the most common biome. As such, the planet looks mostly sand-coloured from space, but there are mountain ranges and oases of different sizes too which can be seen from space.

The transition zone isn't fully green when viewed from space, though it'll be home to many more green spots than the rest of the planet. Green spots are sporadic in the deserts, seen only around a number of larger oases, while the transition zone could have a number of green stretches with smaller green spots in between.

The skies were mostly a pale blue, though in many places it would appear yellowish or brownish due to the everlasting presence of dust and sand clouds. Again, the atmosphere is quite similar to that of Earth, though a lot dryer, and a little thinner. In the deep deserts, it was very rare to even catch a glimpse of the sky. The sand varied in colour greatly: most places had yellow sand, but there was also white sand, red sand and black sand. Kadavan has many types of sand for sure.

Regions
For regions, it is primarily deserts but it isn't the same all over the planet. It was once a watery world, but that was millions of years ago at the very least. Nowadays, Kadavan is primarily a hot desert, though there's various types of deserts. The deep deserts, for example, are very different from the more habitable parts. There's also the whitelands around the north and south poles: these are actually home to some water ice on the surface.

There's also many mountain ranges with far more mild climates, and many large oases that actually sport some surface lakes and a lot of greenery. And there's the Sinking Sands region: a relatively humid area north of the Avikha oasis (where the Avikan originated). While relatively rich in water, the area is even more deadly than the regular deserts due to the toxic gases there and the abundance of quicksand. There's some lakes there too, but those are so toxic that barely anything lives in them.

There's Avikha - a large fertile region on the northern hemisphere of Kadavan. That's where the Avikan originated from, and where they got their name from too. There's the Eastersand and the Westersand - great deserts east and west of Avikha - and also the Great Waste, the Flowing Dunes and the Sinking Sands. There's the Rhakori Highlands, Vhalakis (a small oasis surrounded by mountains, it's found within the Great Waste), and the Kalachi Waste. The poles are known as the Northern and Southern Whitelands.

The Kalachi Waste is a smaller, slightly less violent version of the Great Waste. The Great Waste is a massive desert that spans most of the southern hemisphere of Kadavan: endless dunes, only rarely broken up by mountains and stone plateaus. There's constant sandstorms there, and it's not uncommon for places in the Great Waste to go weeks without sunlight. The Kalachi is a less extreme version of this - it's on the northern hemisphere, on the other side of the planet relative to Avikha. It too consists of endless dunes, but the weather is a little more forgiving there.

The Eastersand and Westersand are home to all sorts of creatures. One'll find a lot of sandworms and sandspitters there, along with countless related species. Sandstalkers can also be found there, although they generally prefer the oases and mountains of Kadavan. Giant sandworms, like Halla'Khan, are sometimes found in the Eastersand and Westersand, but they mostly inhabit the Great Waste and the Kalachi Waste. They'll come up to the Eastersand and Westersand in search of food, but they make their homes in the harsher, deeper deserts.

The Sinking Sands are rich in water, but live is somewhat sparse due to toxic gases and harmful particles in the water. Only some creatures are well-adapted enough to survive there. There's a few predators/scavengers that lure prey into the quicksand and get an easy kill there (they have evolved to be very mobile in quicksand themselves), but there aren't too many creatures there.

The Rhakori Highlands are a mountain range known for having very flat tops, basically massive plateaus.

There is a transition zone between the deserts spanning most of the globe, and the (relatively small) polar zones/whitelands. Plantlife is more plentiful there, it'd have regions that look like shrublands. A lot of this plantlife is mostly short and relatively low to the ground, though. There's little reason to compete for sunlight, since Kadavan plantlife is more likely to receive too much of that. Precipitation, in the form of rain or snow, is also extremely rare, to the point where many Avikan are entirely unfamiliar with it. Kadavan isn't home to any oceans, and has very few places with liquid water open to the surface, so there's barely any cloud formation. The lack of rain also makes it so the plants compete mostly for groundwater rather than surface/rainwater. They'll have very extensive root systems, which mostly burrow deep rather than wide to reach the underground reservoirs, and vegetation above ground level is often minimal.

The transition zone also has a 'dead zone' in parts that are closer to the deserts. It has a lot of rocky plateaus, and the largest ravines found on all of Kadavan. Cracked stone is very common there. Over the eons, the polar regions have been shrinking, with the green belt taking over the areas that are now too warm for frozen water. As this green belt shrinks, it leaves behind a rocky region that's cracked from the changes in climate. It'll be home to massive ravines filled with razor-sharp rocks, and massive stretches of terrain completely devoid of life. While not necessarily the harshest region of the planet - the Great Waste likely takes first place there - the region is very difficult to traverse due to the lack of natural resources and the difficult terrain.

The ravines would indeed have flat cracked stone tops, with steep cliffs and some intermediary plateaus inside some of the ravines. Many of the ravines will be empty at the bottom, but some may have toxic water or razor-sharp rock fragments at the bottom. A rare few may even have some spots with fresh water and some minor plantlife, though these would be rare.

Alongside the rocky terrain of the deadzone, this is likely also where one'd find regions a bit similar to the sinking sands - toxic wastelands home to more liquid water, though the water is contaminated beyond use. Toxic vapours would be a very real threat here.

There's definitely a lot of salt flats on Kadavan, which are found mostly in regions that were one oceanic in the very distant past. You won't find these too close to the polar regions, but rather spread across the globe. A lot of these have been overtaken by the deserts over time, but there's still some massive salt flats to be found.

The whitelands may actually be home to some minor snowfalls, though snowstorms (caused by the same winds that create the sandstorms) will be relatively common. These snowstorms often blow a lot of snow out of the polar regions, causing it to melt and evaporate, which creates a small cloud layer near the poles while also supplying the green belt with additional water (and further shrinking the whitelands). This is likely the only place ever to have snow and rain falling from the sky.

Roads
Back on Kadavan, the Avikan had very few roads, actually. There were some roads within the terves (cities), but not very many since vehicles were uncommon within the terves. Many terves were located quite far from others, so an interstate-like road may seem reasonable, but the climate on Kadavan didn't make them very practical. Such long roads were extremely prone to getting covered by desert sands due to frequent sandstorms, and for a long time the Avikan had very few vehicles at all. Travel by Gad'hur remained common for a very long time. That being said, there were a few extremely long roads built between major terves, often raised up well above the ground.

As for speed limits, there wasn't really such a thing on Kadavan. Traffic was so rare that there were very few strict traffic rules, and outside the terves almost anything was acceptable.

When the Avikan created their first hover vehicles, vehicle usage increased dramatically as things like a Keff could operate anywhere, even without roads and on the roughest terrain. Still tough, personal travel never became anything like what you see on Earth.

List of locations
Rewrite from the "Kadavan locations" codex in Starbound mod.
 * Avikha - Kadavan's most fertile region, the origin of the name 'Avikan'. It is located in northern hemisphere of Kadavan.
 * Avikha oasis - An oasis located centrally in the Avikha region, and the birthplace of Avikan people.
 * Dunes of Avikha - The mountain-sized dunes marking the outer edges of the Avikha region.
 * Vhelin - The Terve of Vhelin, the capital of the pre-exodus Avikan nation.
 * Eastersand - A large desert located to the east of Avikha.
 * Westersand - A large desert located to the west of Avikha.
 * The Flowing Dunes - A large desert located south of Avikha, frequently ravaged by sandstorms. Dunes form and erode in a matter of hours, sometimes even minutes here.
 * The Sinking Sands - A wet region north of Avikha. While rich in water the region is home to large quicksand pits and the air is filled with toxic gasses. Making the region inhospitable to most forms of life.
 * Rhakori highlands - A mountain range in the Eastersand, known for it's flat tops.
 * The Great Waste - A massive desert stretched across most of southern hemisphere of Kadavan. The region is continously ravaged by sandstorms, and combined with it's extreme temperatures, the region is completely inhospitable to Avikan people. It is often referred to as 'Deep Desert'.
 * Vhalakis - A fertile oasis enclosed by The Great Waste. Only the massive mountains allow it to exist in Kadavan's most inhospitable region.
 * Kalachi Waste - A large desert located on the other side of Kadavan, relative to Avikha, on the northern hemisphere.
 * Northern Whitelands - Kadavan's northern pole, one of only two areas with large amounts of frozen water.
 * Southern Whitelands - Kadavan's southern pole.
 * Vha'leihan Mountains - A mountain range on western edge of Avikha oasis.
 * Vas Vha'leih - An ancient Centensian city located in Vha'leihan Mountains.
 * Vhalas Vha'leih - A small Centensian city located on the highest peak of the Vha'leihan Mountains, and the palace to Vas Vha'leih.

Plantlife
Cacti are definitely common there, and they look quite familiar, but on closer inspection you'll find more differences. Overall shape and appearance are familiar, but the cellular make-up is different, and the plants have different kinds of layers to them. The Kadavan cacti evolved on their own, but evolution took a relatively similar path on many planets due to similar environmental circumstances. They are vital to life in the desert.

Known plantlife:
 * Kadavan spice plant - it's fruits can be dried and ground into spices. They're akin to peppers, burning when eaten. The fruits also supposedly taste very bad on their own. Spices can be used as dyes, too.
 * Brasbon - type of cactus that produces soft fibers. Avikan use these to make fabric.
 * Bolbohn - An oddly-shaped, purple plant. It tastes horrible to every alien, except for Avikan, who love them. It is often used in Avikan cuisine, as well as for making purple dye.
 * Dunestalk - a hardy, wheat-like plant. It looks incredibly dry, it could be mistaked to be dead. Avikan use it to make dunebuns, among other traditional foods.

Wildlife
There are countless animal species on Kadavan of course (far too many to document, like here on Earth), but the Avikan only domesticated a few of them on a regular basis. The Gad'Hur is their most important domesticated animal, but various species of sandworm are also used either as pets or sometimes as livestock. Smaller creatures related to the sandstalkers are also rarely used as pets, but they can prove quite dangerous.

Kadavan has giant worms somewhat like those of Dune.

Sandworms and sandcrawlers are actually distinct species, though many Avikan don't know the difference. They are related, though.

Almost all life on Kadavan has leathery fur, yeah. The Whitelands are the only region where furred animals appear, and even there they are rare. There's a few types of animals with fur, some of the most common being smaller relatives of the Gad'hur. Two legs, a short tail and a shorter neck than the Gad'hur (to reduce surface area), and with more stored fats so they're a bit like tiny, fat Gad'hur.

Gad'hur
The Gad'hur are the Avikan's most important domestic animal, acting as mounts and beasts of burden, as well as providing milk. They aren't bred for slaughter, but when one dies their meat, hide and bone are taken and used fully. Besides these two animals, the Avikan keep some smaller relatives of the Gad'hur for slaughter and other types of milk. They are the equivalent of goats and the like, but I've yet to name them (or create sprites for them).

Sandcrawlers
They bury beneath the sand and strike with little warning.

Sandcrawlers are domesticated to some degree too, acting as pets, guards and sometimes being bred for slaughter (for meat, hide and bone all). The Avikan often eat sandcrawler eggs too. Their teeth are especially valuable as well.

There are domesticated relatives of the sandcrawlers too - both large and small ones - but they're not very common.

They only lay their eggs when fertilized. They evolved to waste as few resources as possible, and laying unfertilized eggs was a waste of resources out in the harsh deserts of Kadavan.

Sandcrawler eggs are very slimy, with a thick, fatty slimy outer layer, and usually a dead fetus at the center with some tough flesh. Humans probably wouldn't like the taste.

Sandspitters
Sandspitters are a bit like millipedes in the way they move: they have a large number of small limbs they use for walking/crawling. They can also stand upright allowing them to reach higher places and giving them an advantage in some fights. They aren't very similar to millipedes in other ways, though. Sandcrawlers have no limbs, and are more similar to Arrakis worms. They dig shallow tunnels and extend, contract and bend their bodies to move around.

Sandspitters do have an endoskeleton. They are far too large to use a hydrostatic skeleton, and their limbs (which have bones) also need some central structure for support. Their skeletons can stretch a little more than usual thanks to the special tissue in between their vertebrae.

They spit sand to keep enemies at bay. Sand is stored in a specialized sack inside their bodies.

Sandstalkers
Sandstalkers are a native species of Kadavan, which look a bit like a mix between a cougar and an insect: a big, lightning-fast beast with sharp claws and fangs which hunts many of the other desert creatures of Kadavan

They are the apex predators of many ecosystems, and hunting one is a very impressive feat for the Avikan. Hunting competitions, like the Games of Vhelin held during the Andas Vhelin festival, often require their participants to hunt down a Sandstalker to prove their merit and skill.

Nearly impossible to tame, even when raised from a very young age. They are incredibly aggressive, but also very stealthy. Some attempts at taming them have been made, but most of the Avikan who tried to raise a Sandstalker were eventually ambushed by their "pet" when they weren't expecting it.

Halla'Khan
Halla'Khan is one of the giant sandworm-like creatures found on Kadavan (so not the name of the species, but rather a single specimen). It is a massive, 328 meter long sandworm - making it one of the largest ever recorded. It's relatively slender for its length, but still a massive creature with a gaping mouth full of razor-sharp teeth, both giant ones (like the ones used for making weapons) and smaller ones, lined all along the mouth.

Halla'Khan (also known as the Devourer) is especially (in)famous because it devoured an entire Avikan camp sometime before the Era of Vhelin. The Avikan tried to kill it for centuries, but it proved to be too elusive to track and kill. They managed to obtain a few of its teeth, and crafted weapons from them, but they never managed to kill it. These weapons were given to some of the greatest Elders of the time. After the Thelean invasions started, attempts to kill the worm were stopped, as the beast destroyed several Thelean ships that came too close to its territory. The Avikan believe the beast still lives today, and have given it an additional title: the Thell-Eater. It's become a creature of legend by now.

It's a creature that caused the Avikan great harm, but it's also helped them out massively during the invasions. It's incredibly old, and the thousands of stories about the beast have given it an almost mythological status.

These types of worms can grow a few dozen meters in length, with extreme specimens being even larger. Halla'Khan is one of those extreme specimens.

It crushed Thelean ships in its jaws and underneath its massive body. They try to avoid it if they can: they have nothing to gain from antagonizing the creature, and hunting it down is a waste of resources as they've only occupied Kadavan to retrieve the Centensian relics. Should they ever find it guarding a Centensian ruin, they may try to hunt it down, but otherwise they'll likely leave it be.

It's got a central territory, and some expanded hunting grounds, but the Avikan don't know much more about it. It's theorized that it has a nest somewhere, likely in a massive underground cave, where it rests until it feels the need for food again

{Are there any cults to Halla’Khan? Have any cults appeared after it started including Thells to its diet?}

Halla'Khan has been worshipped by some small cults, both before and after it started eating Theleans. Sandworms in general have long been part of Avikan religions, and were one of the common objects of worship before the Rhaiod emerged.

The first few ships were completely stunned when they detected the massive sandworm emerging from the ground, and had only seconds to respond. They obviously didn't make it, not even having time to fire up the engines and fly away. Later on, some Theleans tried to hunt it down, but they failed: the worm shrugged off most attacks, and would quickly crawl back into the sand when attacked, often after killing a good number of the assailants. Eventually, the Theleans simply learned to be careful and avoid the worm's territory whenever possible.

Halla'Khan seemed to be especially vicious against the Thelean invaders, attacking them far more often than it had the Avikan in a similar time frame. The Avikan theorize that the noise created by the Thelean ships was to blame, but some believe Halla'Khan (who is know to be somewhat intelligent) recognized the Theleans as invaders and lashed out because of that.

Stingwings
Stingwing swarms operate as a single creature, using specialized pheromones to communicate and coordinate. The swarms are led by a queen.

Val'ahr
A highly aggressive cave dweller, the Val'ahr has evolved wings to help it navigate Kadavan's cave systems.

Smaller relatives of the Val'ahr are sometimes kept as pets, and rarely their eggs are eaten, but they too aren't very common.

Vas Vha'leih
Kadavan is home to two Centensian cities: Vas Vha'leih and Vhalas Vha'leih. Vas Vha'leih is the main city, and the Avikan were granted access to it by Rhadeis. Vhalas Vha'leih is the city-sized palace (Centensian cities always came in pairs - a city and a massive palace), which the Avikan never gained access to.

Vas Vha'leih's architecture was much like that of other Centensian outposts seen in the Starbound mod. Vhos Avha'las is a very good example here. Think tall, geometric structures, massive pillars, glowing walls and intricate patterns. Massive hallways connected to countless smaller rooms, but everything was spacious.

Vas Vha'leih was actually built into the mountains. It was also well-hidden: the city was vast, but only the entrance could be seen from the outside, and it was hidden underneath and outcropping of rock with more rocks obscuring the gate from view over great distances.

Vas Vha'leih was settled early in Avikan history - approximately 2500 years before the Exodus - by some nomadic clan whose name has long been lost. They simply became known as the Vha'leihans as time went by. The colony inside Vas Vha'leih grew explosively, but fared excellently for a few hundred years. Around 2150 BF (Before Flight), the population reached a critical level though: supplies fell short, space ran out and the people started to riot. It was the first real civil war in Avikan history.

During the fighting, Vas Vha'leih was damaged significantly, and eventually the Vha'leihans left their home in search of new territory. Some groups went to the mountains to build the first Terves, while others returned to the desert and resumed a nomadic lifestyle. Vas Vha'leih was never truly settled again afterwards. The place had been wrecked, and the entrance sealed. It was only reopened during the Era of Vhelin, and became a sacred pilgrimage site

Nowadays, the Centlars and the Rhaiod have a semi-permanent residence there, but no one clan owns the sacred city. The entrance was sealed again during the Exodus from Kadavan, so the Theleans could not get in, and so far the Theleans have not been able to get in. It's a completely underground structure with an outer wall that's incredibly thick, and made of some of the strongest alloys used by the Centens. The Theleans have no hope of cutting through that. When the city was sealed, all entrances were locked by doors just as thick as the wall, and only an authorized key could open it. The Avikan are in possession of the only known key, which is part of why they are hunted by the Theleans still.

That key was originally gifted to the Avikan by Rhadeis, otherwise the Avikan would never have been able to enter in the first place.

There's some Ce'Tennan vaults and other structures outside of the Avikha region, and there might even be some in the deep deserts. They are generally quite small though, Vas Vha'leih was by far the largest Ce'Tennan structure on the planet.

Thelean presence
The Thelean occupation of Kadavan has been weakening over time: they have already extracted a large amount of relics, and while there's still plenty of Centensian relics left for them to find, their numbers on Kadavan just aren't comparable to the original occupying force anymore. Whether or not the Avikan will be able to hold on to Kadavan is another matter though. Should the Avikan return there, the Theleans are sure to send more forces and the Avikan will be forced to flee again.

There's definitely groups of Avikan that remained on Kadavan. Some of the Vanguard stayed behind to fight the Theleans and give the Nomada time to flee, while other clans just refused to leave. The deep desert clans might have actually survived the invasions, as those regions hold little of interest for the Theleans and are too dangerous to explore, even for the Theleans.

The Thelean presence in the Whitelands is especially light, since there's not much of interest for the Theleans there. It certainly isn't safe to return there, though, unless the Avikan could somehow completely avoid detection by the Theleans' orbital surveillance.

Trivia

 * Kadavan is located in Hetat-B Haros on THEA Galactic map.
 * "One of the story missions I have planned is for the Avikan to send a small party back to Kadavan to locate and retrieve the remains of the Thellhunter, whose location was recently found through new research and combining data from the Nomada archives. It's not as large of an event as taking back Kadavan, but it'll allow players to visit the planet and explore some of the history of the Avikan (and obtain some nice rewards from it, like the Thellhunter's weapon and armour)."
 * There were plans to add new planet types to the Starbound
 * Kadavan once had far greater amounts of water on the surface - there's still a lot of it underground now - but that was long before the Avikan came around. They inherited a few features from water-dwelling ancestors, such as the fin-like protrusion on their backs, but the early Avikan were always land-dwellers.
 * The natural disaster that threatened the Avikan was a massive volcanic eruption - or a chain of eruptions - that could have caused massive changes in Kadavan's climate, and could have destroyed much of Avikha - the oasis where the Avikan developed. Rhadeis was able to intervene and stop this eruption, saving the Avikan from early extinction.
 * [Fight between THEA animals] "Elithia is home to some pretty strong creatures, but nothing too incredible. Kadavan is a much harsher world, and if you count the massive sandworms like Halla'Khan they'd likely come out on top, but the other planet have nothing of such a size so it's not a very fair fight."
 * There were aquatic predecessors to the sandworms on prehistoric Kadavan.
 * There were plenty of clans on Kadavan. A lot of Avikan lived in camps, underground bunkers or Terves. The last one being used by biggest clans as cities. The largest city/Terve is Vhelin, which acted as the capital of the Avikan nation before the Exodus.
 * Haven't yet specified how long a Kadavan year is compared to an Earth year, but while it won't be the exact same, it's relatively close.