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The Laws of Atolia
In Atolia most of the natural laws apply in the same way as they do on our world. The biggest exception is obviously the floating land masses, flying ships, Gates, and the Evermyst.
Floating Islands
The land masses of Atolia float above the swirling Evermyst. The physical mechanism that allows the islands to float remains unknown. However, scholars have noted that the underside of every islands is coated in a few meters of an obsidian like substance. This substance is theorized to be what holds the islands up. This speculation is further confirmed by the fact that certain people can connect with pieces of obsidian that have broken of the underside and they can cause them to start floating again.
The islands also seem to move in complex mysterious ways. The islands some times seem like they can be blown around by the wind, but other times seem to move of there own accord. Some scholars have noted that the islands seem move in coordinated patterns and some islands appear to move together or seasonally move together and apart. A few scholars have postulated that beings living on the islands have a unconscious power to direct the movement of the islands. However, this hypothetically power is unconscious and no one can actively control it. One fact that supports this theory is the fact that certain individuals can connect with chips of the obsidian underside of the islands and make the chips float in the air.
Flying ships
One other important aspect of the world is the prevalence of flying ships. Hundred of years ago people discovered that if you chip off some of the obsidian rock on the underside of all the islands you can use the fragments to make flying ships. People discovered that with training one can connect their mind to the fragment and cause the fragment to float in the air again and hold 1000 times its mass. This is an exhausting process and with extensive training people can maintain the connection for several hours. Due to this long distance travel away from a safe island to land on is almost impossible. Furthermore, if two people both connect to a different fragment and then bring the fragments near each other, both fragments ability to float will be drastically reduced with the smaller fragment being effected the most. This means that only one person at a time can connect to the crystal powering a flying ship. Furthermore, without extremely specialized training one can not swap out a crystal without first landing a ship.
The details of how the connections works means that flying ships behave in a manner similar to water bound ships. The connection to the obsidian allows the crystal to float in the air and the user can determine its orientation, but it does not allow the crystal to move on its own. Flying ships have to gain their power through other means. Depending on the type of ship, this power could be someone standing on the ground and pulling on a rope connected to the ship, or the ship could have sails to push it through the air. However, moving the crystal causes the crystal to resist the movement in a manner similar to the friction caused by water on normal ships. This force is dependent on the amount of mass supported by the crystal and the square of the velocity. Additionally, the grains of the crystal have a distinct orientation, and this frictional force is drastically less in the direction of the crystal grains. A connected user can also slowly change the orientation of the the crystal in a manner similar to the rudder of a water bound ship. This means that handling properties of flying ships are similar to their water bound cousins.
The Magical Gates
The islands in the central city have a unique property not found on any other known island. Early in the islands history a silver cloud would cover parts of the island. Any person engulfed in the cloud would be magically teleported to another island. Initially a dozen or so islands were connected to the main island in this way. This connection allowed a settlement to grow and prosper on this highly connected island. It is said that the Whitehairs figured out how to "sing the silver" into a contained archway. Thus instead of random teleporting fog descending on the island the whitehairs created a series gates on the island that if one walked through them they were transported to a corresponding gate on a different island. The whitehairs even figured out how to link additional islands to the main island by constructing additional gates. As more gates were constructed the city continued to grow. When the schism happened and the whitehairs betrayed the city, the knowledge of gate construction disappeared with them.
Cosmology
Nobody knows for sure what happened and there are many myths and legends about the creation of the world. What happened was in the time before the rifting, the world was a standard fantasy world with magic and technology approaching that of the early iron age. Then some great magical spell went horribly wrong and ripped apart the magical fabric of the world. this caused the land to rise into the air and the evermyst to swirl around the surface of the world.
Principal Geography & Features
The world is composed of shards, floating islands. The shards are composed of the former contiguous land mass. Thus each shard is very unique and varied; some shards came from acient mountians and maitian steep cliff like geographies, while others are flat shards that were formed from flat techtonically stable regions.
The shards themselves vary in size from chunks not much larger than a football field, to a few several dozen kilometers across. A typical size for a shard in the inhabitable zone, close enough to the evermyst to have a enough breathable oxygen, is 1-400 sq kilometers.
The climate and biomes on the shards is highly diverse and depends on a few factors. First, how much rain falls on a shard depends on its latitude. At the equator and 60 gets the most rain, while shards around 40 get very little. The second factor that determines rainfall is height above the Everymyst. Under the evermyst is mainly a ocean, as the sun shines down on the Evermyst evaporation happens and mosture is moved into the air. Low lying shards (0-3500m) are often engulfed in these rain laden clouds and recive lots of mosture. Higher up shards (3500-6000m) only recive rain when large cumulo nimbus clouds form and the large clouds engulf the shards, and thus are only deserts. Past 6000m the shards recive no rainfall and a mostly barren and devoid of life. Shards at 10000m or higher are in such thin atmosphere that no human can survive the lack of oxygen.
Initial Active Setting
I will focus my efforts of world building on the central shards with the teaming metropolis on it.