= Preliminary Design Document =

A preliminary design document can be thought of as an organized list of features.  It describes what you want your product to offer in terms of gameplay, technology and look, without worrying too much about how it will be implemented.  (Of course, if you know that something is impossible, save everyone useless aggravation and take it out now!)

The preliminary design is a discussion document, and it may (should?) go through several iterations.  If you are writing a role-playing or board game, you can start play-testing at this stage, which will help you weed out elements that don't work.  Computer games are a little trickier, since you have no software to play with until much later in the production process; nevertheless, discussing the design document as openly as possible, with other designers in your company and with lead artists and programmers, will serve much the same purpose.

The content of a PDD depends so heavily on the type of game being considered that it is not even worth trying to define a standard.  As an example, here is a partial list of contents for a 3D PlayStation game I once co-wrote:

 * Technical specifications: frame rate, texture resolution and color depth, number of player characters, single and multi-player modes, camera handling, etc.
 * Backstory, including a storyboard for the game's FMV intro.
 * Cast of characters: the player characters and their unique talents, the villain, his ships, the supporting cast, etc.
 * List of the game's environments and the missions taking place in each.  About 1-2 pages of general information on the unique characteristics of each mission (i.e., slippery surfaces, low visibility, types of monsters, race vs shooting, etc.)
 * Special ammunition, power-ups, traps, bombs, equipment.
 * Monsters and the statistics that define them: endurance, hit potential, type of behaviour.
 * Lives, health, resurrections and tagging between player characters.
 * List of moves, including the secret and special-purpose moves appearing in specific situations.

I have seen preliminary designs ranging in size between 20 pages (for a shooter) and 60 pages (for a very detailed strategic sports simulation.)

While great care should be taken not to waste time in endless discussions, when in doubt, keep talking.  Cutting design time short to save money is a sure-fire way to run a production into a wall.  Preliminary design can take anywhere between 4 and 10 weeks for the designer, and 10 to 30 hours for the other people involved in brainstorming.

I have posted the revised design document (an advanced form of the preliminary design) for a pro-wrestling simulation play-by-email game here.  Of course, it is a very simple game, and the document for a commercial computer game would be a lot more complicated, but the level of detail and the completeness, given the subject matter, is about right.