The game design document is the the piecing together of all the game design components.
– the storyline (scripting)
– overall blue print for exactly how the game will be played
– the look of each menu or screen in the game
– the controls for the character or characters
– the game’s goal
– the rules for how you win/lose in the game
– the maps of the different worlds or levels within the game (what is exactly in each world?)
– what can and cannot be interacted with
-what scripted events occurs
– what happens on screen when specific buttons or keys or directions on an input device is pressed
-how the NPC (non-player controlled) characters react to what the player-controlled character does in the game
Enough detail needs to be in design documents for the programmers and artists to be able to know what needs to be coded and created
This makes a quality game!
Once you have all the necessary details in your game design document, the next step is pre-visualization. I like to think of it as adding life to your storyboards. Pre visualizations can add music, sound effects and dialogue to closely imitate the look of fully produced and edited sequences. 3D tools that are used for the production phase can also be used for pre visualization such as Autodesk Maya, Motion Builder, Blender and Autodesk 3Ds Max.
Here is part 1 of a video series of the Making of Resident Evil 5 uses of pre-visualization