The Worldstorm, an immense series of continual storms that forms the southern border of every map of the world, separates the Known World from the Found World, an area recently rediscovered. Once it was thought that the Worldstorm formed the southern edge of the world. Any ship that tried to sail through it either never returned or was found as floating wreckage. The storms themselves are constant and maintain a churning westward movement, never letting up. Ancient legends claim that the gods set up the Worldstorm, but the reason why has been lost as the gods are silent on that topic.
Sometime within the last century, the Moon Gates started resumed opening and closing after millennia of inactivity. They were accidentally discovered and it was learned that they offered passage to lands south of the Worldstorm. The gates are only open for a relatively short period and only during certain moon phases, hence the name. Eventually roughly built ships sailing back from the Found World were able to make it through the Worldstorm with some regularity – indicating the Worldstorm apparently was to keep people out, not in.
When the first ship returned, laden with gold and magic items, everyone took notice. Gold fever spread across the Old World and small wars were fought for control of the best Moon Gates. Expeditions were organized and sent through and rude colonies established.
The PCs are new adventurers that have decided to make their chances in the Found World as a chartered adventuring company. Scraping enough money together to buy their charter, their gear, and Moon Gate passage, you found yourselves in Goldland
Crossing, a rough town built in the ruins of an ancient castle, run by the Chartered Gate Guild. After checking in with the Guild Office, you secured inexpensive lodgings and started looking for adventure.
At the game I added to the description of Goldland Crossing, pointing out how it was situated on the edge of a sea-side cliff. The cliff itself formed a very circular bay with the ruins of a city in it, now uniformly at a depth of 20 feet. Based on the remains of roads, the city used to be level with the fort until magically forced down into the water. The area in Goldland Crossing known as The Docks consists of warehouses and cargo cranes that reach down to the water, 50 feet below, where docks have been built out of stone reclaimed from the sunken city.
The next nearest city ruins now comprise the Mammoth Fall Mines Barony. A nearby mountain was apparently forced to avalanche en mass onto the city below it, mostly burying it. There are now operations digging down into the buried remains of the city and looting it. The original explorer brought backlarge amounts of gold and magic and was made a baron with the right to control all diggings on that site (provided the Crown gets its cut of the profits).
A small fief near Goldland Crossing uses the hollow remains of a 400-foot stone statue as a sort of ready made fort. The statue itself is buried from the waist up and is heavily weathered, so it is uncertain if this was a king, a hero, or a god. It is now the Fief of the Empty God.
I have several more areas named and a base description, but they are not plotted on my sketch map yet. These should give a basic feel for what things are like - an area once very civilized and apparently strong with magic, long ago fallen. This provides the rationalization for: dungeons where ever I want them, wierd tribes and monsters for the PCs to interact with, easy to hand off the DM's Hat to my co-DM whenever I want to play, and a (mostly) lawless frontier starting point that will go through some growing pains as the PCs progress. Sort of like Deadwood, but based in the ruins of an ancient castle. And possibly with less swearing. Possibly.
I'll be using Zak's Urbancrawl Rules for Slacker DMs to map out Goldland Crossing. My city is much smaller than his example in several ways, the most critical being I'm only using six city areas as opposed to his ten. I'll make updates as I expand it and determine how well this method works for me.