Game design is the game development process of designing the content and rules of a game in the pre-production stage and design of gameplay, environment, storyline, and characters during production stage. The designer of a game is very much like the director of a film; the designer is the visionary of the game and controls the artistic and technical elements of the game in fulfillment of their vision. Game design requires artistic and technical competence as well as writing skills.
Game designers will use a Game Design Document (GDD). The GDD will be the bible which your team follows during pre-production and production of the game.
So What Is Inside A Great GDD?
In the Anatomy of a Game Design Document Part 1, Gamasutra explains it all for us;
The purpose of design documentation is to express the vision for the game, describe the contents, and present a plan for implementation. A design document is where the producer preaches the goal, through which the designers champion their ideas, and from which the artists and programmers get their instructions and express their expertise. Unfortunately, design documents are sometimes ignored or fall short of their purpose, failing the producers, designers, artists, or programmers in one way or another. This article will help you make sure that your design document meets the needs of the project and the team. It presents guidelines for creating the various parts of a design document. These guidelines will also serve to instill procedures in your development project for ensuring the timely completion of a quality game.
The intended audience is persons charged with writing or reviewing design documentation who are not new to game development but may be writing documents for the first time or are looking to improve them.
In Part 2 of Gamasutra’s article, we learn that size does not matter;
[GDDs] are often so full of ambiguous and vague fluff that it was difficult finding the pertinent information. So why does this happen? Because the authors didn’t follow guidelines. This article is part two of a two part series that provides guidelines that when followed will ensure that your design documents will be pertinent and to the point. Unlike the authors of those prodigious design volumes, I believe in breaking up the design document into the portions appropriate to the various steps in the development process – from concept and proposal to design and implementation. I covered the first two steps in part one of the article, providing guidelines for the game concept and game proposal. This part will provide guidelines for the two heaviest undertakings – the functional specification and technical specification, as well as some guidelines for the paper portion of level design
You can follow Creating a Game Design Document advice or start with an existing GDD template. Here are some great examples. Take your time and look over each. Craft your own template that works best for your needs, and the needs of your client/boss/team.