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Computer games are made to fulfil dreams.

Some games are light entertainment, designed to while away a few minutes with a puzzle or a simple challenge. For those kinds of games, there's no need to discuss a design philosophy in detail.

But the fundamental goal of a larger game, as I said on my home page, is to take you away to a wonderful place, and there let you do an amazing thing.

Books and movies can't do that. They can take you away to a wonderful place, but they can't let you do an amazing thing. That's the power of interactivity. That's what makes this medium unique, and that's what makes it important.

Therefore, the design of a game begins with the question, "What dream am I going to fulfil?"

Perhaps it's a dream of exploring a dungeon infested with monsters. Perhaps it's a dream of coaching a football team. Perhaps it's a dream of being a fashion designer. But before you do anything else, you must dream the dream. Understand it. Feel it. Know who dreams it with you and why.

Interactivity is the raison d'être of all computer gaming.

The next question is this: "What is the player going to do?"

We concentrate so much on the artwork, the sound, the music, the motion capture, the video, that it's easy to lose sight of this question. Interactivity is the raison d'être, the reason for being.  We have to know what the player is going to do. What actions, what activities, will fulfil the dream?

In addition to actions, the player also has goals. It may be that the game is really a software toy, and is meant to be played with without goals. But in traditional gaming, the player is trying to achieve something, a "victory condition." For goal-oriented games, defining the victory condition is closely related to defining the actions taken to achieve it.

In any game more complex than a puzzle, the player is playing a role. It may be a medieval adventurer, a military commander, a business tycoon, an athlete, or it may be something abstract and almost indescribable. (In the coin-op game Tempest, the player was a sort of two-legged spider with a machine gun.) Defining that role -- its goals, its limitations, and above all its actions -- is the second step in game design.

 A game takes place in a world.

Any computer game takes place in some kind of a world, by which I mean a physical space, but also an intellectual space, an emotional space, an economic space, and an ethical space.

 The physical space describes all the sights and sounds, the things that the player can see and hear and touch and speak to in the world. Pictures and sounds and language are used to portray the  world, and to create not only its physical appearance but also its tone and mood. The definition of the physical space helps to establish the intellectual, emotional, economic, and ethical spaces.

The intellectual space describes the thought processes that the player will take, the things that she will be required to think about. These can be extremely complex or extremely simple; they can be extremely abstract or extremely concrete. But all games have an intellectual space, a set of rules and ways of reasoning about the game.

The emotional space describes the kinds of emotions the player should experience and the kinds of emotions the characters in the game will display. Fear, triumph, sadness, amusement, and suspense are common elements of the emotional spaces of games. All too often, so is frustration, although rarely by design!

The economic space describes the flow of resources into, around, and out of the game. This need not be money; it can be ammunition, armor strength, "health points," magical power, or any other valued resource which changes in response to the player's actions. The economic space includes a mathematical model which describe how these variables change, and designing that model carefully is vital to creating the game's balance. The victory conditions are usually defined in with reference to elements in the economic space.

The ethical space describes the system of ethics in place in the game. If a game involves concepts that people have moral feelings about (theft, destruction, killing, conquest, democracy, protection of the innocent, and so on), then it must reward, punish or ignore the player's choices when confronted with a moral decision. Sometimes simply ignoring an action sends a powerful moral message in itself.

This is just the beginning.

There's a vast amount more to computer game design. A game's design is informed by its intended audience, by the features of machine it is being made for, by the budget and schedule for its production, by the strengths and skills of the people who are building it. All these things affect the way a game is designed, but the questions above are the ones I think about first. If there is ambiguity or uncertainty about their answers, the game is in trouble. The answers may be revised in the course of production, but they should always be clearly known by all the people building the game. Only through a collective understanding of the dream can they work together to fulfil it.