First, your characters have so far lived their lives within a fairly large region known as the Solar Plains. Moderate climate, wispy clouds here and there but an otherwise clear sky most days, except for on the horizon. The horizon is shrouded in mist. Above the mist is what appears to be an absolutely massive dome that makes up the sky. At the apex of this dome is the sun. The sun is always directly overhead and there is no night time. Your characters have never experienced night time and do not know what a night sky looks like, nor do they even have a concept of stars. The sun takes up a massive 50% of the sky.
Within the Solar Plains are a variety of towns and territories that so far have always gotten along peacefully with an abundance of resources for all. Plenty of food, water, clothing and supplies, etc.
There are conflicts here and there, but nothing major such as war. At least not during your lifetimes, however long those may be. The dome appears to be painted or carved, despite it being astronomically large.
The images depicted on the dome look like far away worlds or landscapes Many religions and mythologies have sprung up around the mystery of the places depicted on what Solar Plains people call the Skyglass. Some say it’s where their god(s) reside, watching over them.
There are three main kingdoms in the Solar Plains. First the Tralestas, a royal Elven bloodline that has long ruled the north-western half of the Solar Plains for millennia, maintaining massive farmlands and exporting grains and all manner of crops. Tralestans are primarily Elves and half-elves but many others have migrated to their kingdom and prospered alongside them, offering their services, goods, and labor.
Second is Withelm, ruled by the royal Withelm family. Withelm is a mostly human kingdom that rules the north-eastern portion of the Solar Plains. They maintain an abundance of water due to the natural springs that come down from the mountains at the back of their territory. They export this water in exchange for other goods they need.
Third we have the Dominion. They claim the southern portion of the Solar Plains and largely keep to themselves. Not a lot is known about what goes on within their massive stone walls but occasionally they will send representatives to political meetings to ensure participation in any larger affairs happening outside their borders. These representatives always appear somewhat reserved and mysterious, but have always been respectful.
Amidst the massive lands of the three kingdoms are dozens of smaller villages. Due to the relative peace and abundance of goods, the lines between the first two kingdoms have been somewhat blurred. In other words, most people and villages don’t seem to pay much mind as to what territory they technically fall under.
Without war for millennia martial and defense training is not as abundant as it once was, but much like modern day many still train in a variety of martial arts for fun and tradition.
Your characters can have backstories from anywhere in the solar plains. If anyone wants to be an outlander of some kind you can make your character be from the Blistering Sands, a region just west of the Solar Plains. Pretty much a wasteland but it’s where wanderers tend to end up when they want to live away from society. It’s scorching hot and wanderers pretty much depend on hidden caves and occasional rain in order to make a go of it out there. There are also the mountain ranges behind Withelm. They are under constant watch from Withelmian guards because the natural Solar Springs come down from the mountains and the water is their primary resource and export. They don't take kindly to folk messing around in the mountains, but the mountains are quite tall and vast and a wanderer or ten has been known to get around without too much hassle.
I will allow one person to be from the Dominion. First come first serve. If you choose to hail from there then your backstory will be heavily influenced by it and I’ll need to help you build it in private so as not to spoil any mystery for everyone else.
Nobody is required to hail from the Dominion, but if one person really wants to then let me know ASAP. PJ already took this option.
Time is kept by traditional clocks and watches and people do sleep during normal sleeping hours. It's just not night time outside. Most homes are built with very accurately cut shutters so as to block out as much light as possible during sleeping hours.
The most common issue in the Solar Plains is fire. Accidental brush fires are somewhat common. Also the occasional thunder and lightning storm occurs and can spark fires as well. The dry climate under the constant sun makes it difficult to keep fires under control. Withelm is known for its practitioners of the Arcane Arts and often sends out its own mages to help quell fires that threaten crops and homes.
There are a few main religions, though you are free to invent your own and I will incorporate it into the story.
The Pyritans believe in the god Pyratesh. They believe the sun is her celestial palace and you may hear many individuals refer to the sun as "the goddess", "the palace", or they may even refer to the sun as Pyratesh herself. Pyritans are the largest religion. They believe the world to be flat and that no matter where you travel Pyratesh will always be there in all her glory, providing energy and light for all she deems worthy to be in her presence. They believe that when they die their essence will join her in her celestial palace, adding to its shining glory.
A group of Pyritan extremists that operate as a criminal underground. Nobody is sure if they actually exist or are just the product of myth. It is rumored that these extremists believe Pyratesh is actually a malevolent god due to the observation of occasional "sun spots" throughout the centuries. Legend has it that over time some Pyritan theologians have come to believe that the periodic black marks on the sun signify a darker truth about Pyratesh.
Sphaerans are less obsessed with the Sun and focus more on the surrounding dome, which they refer to as the "Skyglass". They spend an inordinate amount of time studying the images depicted on the dome. Massive intricate paintings or carvings depicting fantastical looking places. Many believe these paintings were created by gods and represent real places that one could travel to if only they had the divine means to do so. Many stories and myths are told about these places. Most Sphaerans believe that their spirits will travel upward to the Skyglass upon their death, where they will be judged by a group of unnamed gods they call the Glass Keepers.
Sphaerans believe that those who are judged worthy will end up in the most divine region of the Skyglass, directly behind the Sun in the regions that are hidden by the sun itself. They believe that the Glass Keepers hand out judgements in degrees, and those less worthy than others end up in the farther away outer regions of the Skyglass that are not blocked by the sun. In contrast to other religions, Sphaera is the only major religion that holds the belief that the mortal world is round rather than flat.
Devout Pyritans and Sphaerans have been known to have heated debates over their beliefs, but the relative prosperity that the Solar Plains have enjoyed for more than a millenium tends to keep people from getting too heated. If there is any deep-rooted activism in the name of any religion then it has largely gone unnoticed by the majority of the population. Both Sphaerans and Pyritans live happily side by side and no one religion seems to dominate any particular kingdom. In fact, even members of the royal courts themselves have differing beliefs from one-another. This is a rather remarkable fact given that ancient wars of the past appear to have been fought primarily over religious beliefs. The contemporary religions of the Solar Plains are tame echoes of their ancient counterparts.