Uranus
La Belle epoque Cloud City with gears glued on
Summary
The people of Uranus are as eccentric as their giant blue windswept sideways-rotating nothing-but-air-and-slush planet. Theirs is a steam-powered culture of bodgers, scroungers, and poseurs; they are not as interested in the science or engineering of a thing as the aesthetic of it (and bonus points if it works!). Their chief sole exports are hydrogen fuel and the best pilots in the Silver Millennium, and their imports are bloody near everything else. Uranians live in a Gilded Age, a society where the huge dichotomy that exists between the wealthy few and the working class, most of whom toil on the steam-generator platforms and hydrogen farms, is breeding discontent, highwaymen, and union activists.
Geography/Nature
Uranus is an odd planet indeed. It rotates on its side, for one thing. For another, it's all air and hot ice -- there's no solid core. There are constant winds no matter where one is, reaching speeds of hundreds of miles per hour in some parts of the atmosphere. Pilots unused to flying through them can find themselves quickly dead and their ships joining the other wrecks drifting on the surface of the mantle. The only thing it has going for it is hydrogen, and lots of it.
A narrow, pleasantly mediterranean band of habitable atmosphere sits along the equator just above the lightning-riddled hot-ice soup of the mantle and below the frigid tropopause, and this is where the Uranians built their floating cities. The days cycle short and fast, the distant sun skimming the horizon through the persistent fog and clouds. The uppermost layer of atmosphere catches and diffuses the weak sunlight, causing the sky to shine with a lovely cyan glow.
Because there's nothing solid to build on, cities are suspended in the air beneath platforms supported by masses of helium-filled airbags. They are structured like inverted hollow cones, with walkways and stairs and ramps spiralling down towards the bottom. Each city has an aerodrome at the top to service personal and commercial aircraft as well as the massive intercity sky-trains. Hydroponic technology imported from Jupiter abounds; the outer surfaces of the cities drip with plants both decorative and useful (but mostly decorative). The upper classes live closer to the top tiers of the cities, lower and working classes (called Danglies) live toward the bottom; shops and businesses line the interior until you get below a certain level, then it's all slum.
There are no native lifeforms.
History/Culture
Originally settled as a hydrogen mining operation, the descendants of the first colonists on Uranus are now society's wealthy elite, and they control everything. They comprise the hereditary council called the Aetherium, headed by a representative of the Crown (usually the Heir) as Plenipotentiary. Because nearly everything has to be imported, maintaining positive relations with the rest of the Empire is vital; the members of the Aetherium are expert wheeler-dealers and barterers and middlemen -- and con-men and thieves if it comes to it.
Steam is what really runs Uranus. Steam engines of every shape and size are ubiquitous; even electricity is generated by steam, on platforms near the sweltering bottom of the habitable zone and transmitted to the cities via Tesla towers. The towers also serve to transmit radio signals. Wireless is a popular and common form of communication, the Uranian equivalent of the internet, and most everyone owns a crystal set or has access to one.
Nearly all of the tech on Uranus is either hand-me-downs from Mercurian sources or bodged together out of stuff scavenged from derelict extra-planetary transports. The Uranian people themselves, tall, lanky magpies with the attention span of gnats, aren't so much innovators as creative upcyclers. Everything is adorned with brass and steel fittings and elaborate little gingerbread decorations. And most everything works, even if it is not particularly useful. ("I say, old horse, what's this contraption of yours do?" "It goes PING!" "...That's all?" "Why yes, yes it is!" "JOLLY GOOD SHOW THEN")
But the true Rube Goldberg-ian ingenuity of the Uranian people can best be seen in their aircraft. There are flying machines of all shapes and sizes, from personal hydrogen-fueled glider-sleds to practical two-seater aeroplanes to luxurious floating yachts to enormous steam-powered intercity sky-trains. The pinnacle of Uranian aviation are the racing planes, fast and nimble single-seat biplanes that are raced on circuits between the cities. The air races (more to the point, wagering on them) are Uranus' national pastime; successful air racers are like rock stars who get invited to all the best soirees and social events and shop at the finest couturiers and find themselves held up as heroes.
The races are the purview of the wealthy, and are no escape from the drudgery for the Danglies. Some, however, find another way out. They become Raiders, outlaws who attack luxury yachts and transports and rob them. These aerial highwaymen are incredibly organized, working in small clans each with their own turf, coordinating their efforts over radio via cryptic "numbers" transmissions. (The "numbers" station, its coded messages interspersed with cheery music, has become popular amongst the trendy youth; they don't care what it might mean, they just think it sounds cool.) Raider ships are built from scavenged yachts, modded for speed and heavily armed. They tend to not kill unless necessary; their aim is stealing loot and tech.
Some say the use of the Vapours, an addictive combination of chemicals that emit gasses akin to a cross between nitrous oxide and opium, is the reason for the Danglies' predicament. (They say this while taking a drag from a Vapour pipestick.) The Danglies counter that 1. the toffs use the Vapours to keep the workers stoned and biddable, and 2. most Danglies can't afford the good stuff anyway. Regardless, the gap between the haves and have-nots is more like a chasm, and is only getting wider.
Suggested Concepts
Steampunks; Makers; scavengers and salvage operators (though they prefer the term "resource recovery experts"); carpetbaggers from other planets; pilots; pilot trainees; aethernauts; society ladies (and gentlemen); wanna-be toffs; Danglies; Raiders; Vapour addicts; middlemen; gutter-snipes; con artists; if it fits the trope it's ALL GOOD.
Silver Millennium: Uranus