Ancalagon is the capital-planet of the titular empire; it's also where Wreck lives.

Ancalagon is a young (age < 2.5 Gyr) exoplanet orbiting the F2-class star Smaug. As it still has much of its internal heat, and it also has a metal-rich composition, Ancalagon is highly volcanic. Near-continual eruptions create a thin layer of sulphur dioxide and particulate dust in the planet’s upper atmosphere. This gives it a distinctive shiny appearance when seen from space. Whilst the sulphur dioxide layer keeps average temperatures down somewhat, they’re still uncomfortably-high, averaging 32°C across the surface. Also, the resulting acidic rain inhibits plant growth. The combination of excessive temperatures and inadequate and somewhat-toxic rainfall has given the planet an extensive and near-lifeless desert belt around its equator.

Ancalagon’s soils are young, thin and mostly-synthetic in origin. Consequently, they are easily-damaged and this combines with the dry climate to make agriculture difficult. Crop yields tend to be low on Ancalagon, even once the plants have been engineered for tolerance to the harsh conditions.

This also poses more problems for mammals such as cis-humans, due to their higher demands for food. Keeping all that body mass actively-warm needs a lot of energy.

Ancalagon also has an uncomfortably-high surface gravity, at 1.28 G. However, its atmopshere is relatively-thin - this is due to the hard UV off of the hot, white star Smaug. (It forces photo-disassociation of molecules in the stratosphere and upper atmosphere; once broken up, the lighter chemical species are free to escape to space. This loss of mass has lowered the surface pressure.) The high gravity poses problems for cis-humans - even small falls can break bones, and the extra pressure on the heart and musculoskeletal system can lead to numerous illnesses. Travel to Ancalagon is not recommended for people with cardiac problems.

Also, the emissions from the omnipresent volcanoes have served to reduce Anacalagon’s ozone layer. Combining a thin ozone layer with the high UV output of F-type stars, this means that sunburn, retinal damage and even skin cancer are continual risks for baseline-human visitors.

Whilst technically-inhabitable, Ancalagon is a difficult environment for baseline cis-humans. It was only settled in the first place out of sheer desperation, during the Final Century Pre-Exile, as Old Earth slid towards its final eco-catastrophe. By this late stage, all the more clement worlds within the Exile already been taken. It is a marker of how unappealing Ancalagon was that the planet was literally the third-last world to be settled before 0 PE. However, the people who came to Ancalagon found themselves with nowhere else to go and no possibility except to try and make a go of their awkward circumstances.

The sheer practical difficulty of living on Ancalagon was a major factor in the Ancalagon Development Corporation’s decision to begin a process of genetic and phenotypic modification within the colonial population. While this was initially a modest project (a few tweaks to skin and eyes for UV tolerance, and some changes to the skeleton to account for the gravity), it rapidly became more ambitious. Whilst full speciation wasn’t intended, nonetheless that has been the effect of six centuries of genotypic drift. In fact it’s a matter of substantial debate whether the Ancalagonian ‘dragons’ even count as a clade within the Exile’s pan-humanity, or whether they’re now so different that they need a category of their own.

Certainly, it's been several centuries since the dragons stopped thinking of themselves as any kind of pan-human (although the common historical origin is, of course, a matter of widespread knowledge). The ADC is also part of the past, having been overthrown during the revolution that eventually resulted in the establishment of the Empire.