It is a Small World

Every GM eventually begins to build their game environment. Even if they use a 'canned' premade environment, eventually they will want to put their own stamp on it. This is a good thing. It takes much less time and effort than you might think, after all authors do it all the time. Now Every world builders and GM should have this rule in mind.

Only spend as much time on a world, map, scenario, or NPC, as the amount of play and enjoyment it will allow. A masterpiece is not a masterpiece unless someone actually sees it. Spending three months writing a three session scenario is a waste of good gaming time. This is also known as the Mona Lisa rule.

You see, your job as the builder of a game environment is to give the environment the illusion of completeness. You do not need everything; you need 'just enough'. In aspects of the environment that the players will interact with, you will need a great deal of detail. In aspects that players care very little about, just one or two details will suffice.

This can mean vague maps and rough city sketches. If perfect maps are not available, why make them? If you don't emphasize maps, the players won't feel required to have them. If you want, there are thousands of historical maps and floor plans out there, adapt them to your needs to save yourself the trouble of making them.

The important things to consider when creating a game environment are: Terrain and Weather, Flora/Fauna, Resources, Races and People, Cultural Overview, Calendar and Holidays, Standards of weights and measures, Institutions (Religions, Governments, Guilds, Large Businesses), Laws and Morals, Family life, Social Classes, Political, Economics, Religion, Technology, Transportation, Arts/ Literature, Shadow (Criminals and those in the shadows of society), Power (Magik, psionics, etc), Paranormal (beasties, monsters, etc), History of the area, and Rule Modifications to accommodate the game environment.

One of the best trick for gamers is to consider the game environment the single most important character in your game. Treat it that way. It needs a concept, a physical description, statistics/ abilities (defining what it can do), and a history, just like any character. Invest the effort to bring it to life. GMs: Each sub-section of the environment (a nation, a neighborhood, a building, a forest) can be considered its own character. The process continues with more 'character creation'.

One of the problems with creating a unique game environment, especially a more exotic world, is that you can leave your players 'out of the loop' because they do not know the culture and the world. You think the game is whizzing along while the players begin to look at you blankly because they don't know why things are happening. Sometimes GMs get too wrapped up in the creation to forget that they have to communicate their world to others. They need to create a world pack, or have narrative moments of some kind, to explain these things to the players.
When setting up a campaign and creating a game environment, a GM should create a world pack. Part of the packet should be information explaining the campaign setting. This should all the information they (the players) need about the game environment and the world it represents. This does not have to be in large, long, encyclopedia like sections. It can be a collection of important pieces of information, in simple short sections- or even one line entries. Focus on the concrete things, such as daily life, food, travel, how the dead are treated, marriage, and some such. Those are things the players will really need to know.

Include as much as you are able, as it will save you having to explain things in the future.

Remember that you are surrounded by 'experts'. Utilize the rest of your troupe's expertise and interest. Incorporate those things into your world, and you will a) get work done without doing it and b) no have to worry about the 'expert' shreading something of your world because they 'built' that section.

Finally, continuity over a campaign is all important. Building is a never-ending process. During play, many things will pop up about the game environment that was not fully considered during the initial phases of construction. Just fill in the details, keeping in mind the existing decisions about the game environment. Every now and again, do a revamp of the environment. You have added new bits to the top, start from the bottom and build back up.