I crafted Kaye to give the players as much freedom as I can so they can fully immerse themselves in the story of the campaign. This immersion requires consistency which I implemented using three devices. The first device is the use of recurring NPC's, the second was to create a sensible story, and the third and final was to define both the city and state where the adventures will take place.
Consistency is important so the players can rationally understand the game world. That understanding allows them to plan ahead, measure their actions, and judge the actions of the NPC's.
The recurring NPC's all have a complete player's sheet. They could very well be used to play an actual character. Aside from that sheet, they also have at least two defining characteristics. These vary from NPC to NPC, but they usually define their personalities or physical appearance.
A sensible story is created like a puzzle by fitting every piece of information the players receive while playing. If any piece does not fit, there must a good reason for it. If that reason is nonexisting or weak, than that piece should be removed for it does not contribute to the story.
For example, if a thieves' guild is described as having only male haflings all the encounters that relate to that guild must follow that logic. Any deviations must be described to the players as soon as they see it and the explanations must make sense within the world context.
The more the players interact in the world, the more context or background information needs to be taken into account for the continuation of the story. As time passes, the world in which the players adventure comes to life allowing the players to live their characters within that world.
Finally the cities and state are described visually in a map. That map provides the players with distances between towns, the overall terrain and the city names. The cities are visually described in maps just like the states, but those maps do not contain exact proportions. The city maps only provide the players with the links between districts, their overall location and finally the size of the city based on how many districts it has. Each of the districts is then described by its particular name, their general social class, the kinds of business or other important locations, and finally a series of encounters that further enforce their own unique characteristics.
The Kaye campaign aims to be consistent, so the players can fully immerse themselves in the story that takes place within it.