Geography, Countries, and Culture
The world is flat. It looks like this:
Roman Empire
The Roman Empire is located in the continents corresponding to Europe, northern Africa, western Asia, and North America. Specifically, it contains Brittania, which contains Londinium. The language is called Latin, but is in fact almost identical to Earth English. The leader of the Empire is called Caesar (formerly "Emperor", but it was renamed when it was first held by a woman).
The Empire uses metal coins for money. A gold is eight silver, a silver is eight copper and is allegedly kept at about a basic day's wage but is in practice usually a bit higher, coppers can be physically broken in eight and also are tied to a fluctuating number of black pieces so that inflation can happen.
Slavery exists. People become slaves via the Empire conquering new places, debt, parents selling their children, and being born to slave parents. Power plants are run almost entirely by slaves, supposedly because it's easier to teach the relevant skills to children who don't learn other things.
Jesus is a currently-alive spiritual leader and activist. He is planning to maybe get very publicly executed by the Empire.
Corporal punishment is common in the judicial system.
Arbiters are a group of seasonchanges who are really dedicated to providing impartial judgments on things.
Association of Realitists Republican Empire
Is having a Cold War with Rome. Contains the parts of Asia not covered by the Roman Empire, including the Indian subcontinent. Speaks Surran.
Pacifis
Australia. Was underwater for a few strong years before the stars made it resurface, at which point it became home to a culture which dedicates itself to philosophy.
Archipeligo
An alliance of various islands and also various non-islands, which has a few base rules and otherwise lets its member nations set their own laws. (It definitely has member nations, with rich and varied cultures, instead of being a homogenous green mass. One of them is known for its tourism industry and its weird rivalry between surfers and bikers. Another has a ton of winter solstices living there even though they don't especially involve themselves in the government.) Archipeligo has five or six dominant languages that most people speak at least one of.
Verona
A country by the Great Lakes, surrounded by Rome. Ambiguously part of the Archipeligo, depending on who you ask. Run by New Year's gemini. Anyone who physically gets there can stay, no questions asked. The downside is that sometimes one of the New Year's gemini will take a liking to you and drug you and keep you as a sex slave.
Other World Languages
Esperanto is is locally called Paroleblo and is not a conlang. Several other languages are combinations of some Earth languages.
General Culture
Homosexuality is viewed as an odd person thing, and two even people being gay together is seen as unnatural.
Since days are longer, people tend to have vocations, hobbies they are sufficiently devoted to that they are basically second jobs.