When I first sit down at my PC to start working on a game I pick something already popular to base my game on. For example I got the idea for my latest game design document from Harry Potter. After I have an idea on what type of game I want to make I then do as much research as possible. The research can range from some what Boring such as internet research to something fun like watching movies or shows about the same subject. For the research for my game I am working on now I am watching all 4 movies that have been released to date! Once the research is complete I will sit back down at my PC and make a outline of key events, places, creatures and so on from the research that I can base events from my game on. Once I have the outline I will then start crafting my game world and story based on the research and my own ideas. What I end up with is a world/story all its own.
Outline of steps:
-Develop the world and story
Alot of times during the develop step I spend time trying things out in the game engine that will be used and seeing how things would look before putting it on paper. That way when the design doc. is finished you will have some idea that you will be able to do what you want! Also alot of times the research doesn't end when that step has been completed! There maybe times when you will need to go back well developing the game world and story and do some more research.
Well I hope you all enjoy reading this and it helps you with your next game! Any questions, comments, or ideas feel free to leave them!