This part of the process has yet to start.
This should be a separate document that is as complete as possible.
This is the opening scene of the game, whether it is a movie, splash screen, or a flash of the title. Be as descriptive as possible and supply a story board when necessary.
This is the upfront and in-game menu system. Be as detailed as possible with concept art and font types.
Describe in detail how the control system will work and how the user can change it.
Describe the background music and event sounds that will need to be created. Also, discuss any voice acting that needs to take place.
This is the in-game camera view. Identify where it is to be placed: first person, second person, third person, or side. Also, describe how the camera moves within the environment.
Describe each of the characteristics about the game engine or provide an assessment of a few game engines based on the following:
http://www.devmaster.net/engines/
The story is everything
Identify the location of the puzzles within the story. Also, describe the puzzles indepth.
Go into detail about where and what the player can do in each area. Is it a linear area or can you just wander around? The more they can wander the better.
Identify all the resources available to the player. Also, try and set an idea of how much (this will be tweaked over the development of the game). The resources are everything in the game from guys to gold.
How many are there and what style of game play do they employ.
Describe all the units and or weapons that will be used in the game. Be as detailed as possible.
At a minimum describe how the AI should behave. This piece is more for the expert to go into great detail. Work with the expert closely to get a good design.
For a strategy game, testing will be part of the development more so than the other genres. Take this into account and go into some detail as to how it will be worked into the development cycle.
Describe all the missions within the game. Also, include the mission objectives for each mission.
Decide if this will be a identical replica of the real world or if it will be something that's familiar to the real world but is not technically accurate.
If this is a replica then technical manuals will need to be reference. If this will be the latter then describe how the physics will be close to the real world.
Cite the rules.
Identify which roles the player will be. Will he be a single athlete amongst AI or will he be coaching the team?
This section maybe included in other genres but it is most prevalent in sports. You need to decide if there will be any licensing. If so, be sure what is licensed and what is not. Anything is licensable, for instance a signature move could be licensed.
How will this be done? Will you use motion capture or a highly skilled animator?
Identify the characters.
Describe in detail what moves the character has and describe what button sequence initiates the moves.
Does the character have a weapon? Do they wear clothes?
They are simple games keep it that way.
Describe all the things a player can do in this world in detail.
As stated above, work with the expert in the field to accomplish what you want.
What is the player to learn by the end of the game. Describe the game in detail.
Describe all the puzzles in the game. Or if it is one algorithm that creates each level, describe the algorithm. Also describe or create concept art for the look of the game.
This is an addition to one of the previously mentioned genres. The components that make it online is the communication infrastructure for the clients and servers to talk.
Describe what the server will store and process.
Describe what the client needs to display the game. Will there be in game chat?
What data needs to be transmitted between the client and server. Try to keep this as small as possible.
The interface will need to contain a piece to find games and or other players.
Most of these elements will have their own design documents.