Realism and Abstraction
As we said in Chapter 2, games can be divided very roughly into two categories, realistic and abstract. Realistic games make an effort to model the real world, and when playing them you can rely on real-world common sense. Abstract games bear little resemblance to the real world and have arbitrary rules that you have to learn somehow. However, it isn't really that simple. Realism is not a dichotomy , but a continuum. All games, no matter how realistic, represent an abstraction and simplification of the real world. Even the multimillion-dollar flight simulators used for training commercial pilots are incapable of turning the cockpit completely upside down. This event is (we hope) so rare in passenger aircraft that it's not worth the extra money it would take to simulate it.
Players and game reviewers often talk about realism as a quality of an entire game, but, in fact, it is a quality that differs in individual areas. Many games have highly realistic graphics but unrealistic physics, or realistic economic models but unrealistic user interfaces. For example, a good many first-person shooters accurately model the performance characteristics of a variety of weapons ”their rate of fire, size of ammunition clips, accuracy, and so on ”but enable the player to carry about 10 of them at once with no reduction in speed or mobility. Therefore, realism is not a single dimension of a game world, but a multivariate quality that applies to all parts of the game and everything in it. (If you're mathematically inclined, think of realism as a vector over every aspect of the game, with values ranging from 0, entirely abstract, to 1, entirely realistic. However, no value will ever equal 1 because nothing about a game is ever entirely realistic ”if it were, it would be life, not a game.)
The realistic/abstract dichotomy is mostly useful as a starting point when thinking about what kind of a game you want to create. If you're designing a cartoony action game such as Banjo-Kazooie , you know that it's going to be mostly abstract. As you design elements of the game, you'll need to ask yourself how much realism you want to include. Can your avatar be hurt when he falls long distances? Is there a limit to how much he can carry at once? Do Newtonian physics apply to him, or can he change directions in midair?
On the other hand, if you're designing a game with a presumption of realism ”a vehicle or sports simulation, for example ”then you need to think about it from the other direction. What aspects of the real world are you going to abstract? Most modern fighter aircraft have literally hundreds of controls; that's why only a special group of people can be fighter pilots. To make a fighter simulation accessible to the general public, you'll have to remove or simplify a lot of those controls. Similarly, a fighter jet's engine is so powerful that certain maneuvers can knock the pilot unconscious or even rip the plane apart. Are you going to simulate these limitations accurately, or make the game a little more abstract by not requiring the player to think about them?
As we have said, every design decision you make must serve the entertainment value of the game. In addition, every design decision must serve your goals for the game's overall degree of realism. Some genres demand more realism than others. It's up to you to establish how much realism you want and in what areas. During the design process, you must continually monitor your decisions to see if they are meeting your goals.