One could apply a similar test to computer games. If one is playing a game ofUnreal
Tournamentand cannot tell if the opponent one is playing against is a human opponent
or a ’bot, then one could say that the game passes a limited version of the Turing test
and therefore possesses some sort of artificial intelligence. However, in actual practice,
even if the game had failed that test, people would have said that the game has artificial
intelligence, just not really good artificial intelligence. When game developers talk
about artificial intelligence, they do not mean the computer’s ability to trick players into
thinking they are playing against actual human opponents. Instead, game developers
refer to whatever code is used to control the opponents that players battle as artificial
intelligence. In AI research, the end goal is to simulate the human mind. In a game, the
ultimate goal is to make sure the game experience is fun. How the game reacts to play-
ers’ actions is determined by the game’s AI, and thereby the quality of the AI
determines how fun and challenging the game is. The reactions of the game may be
completely random or completely logical; in either case the code that controls those
reactions is referred to as the game’s artificial intelligence.
Consider a game likeCentipede. The AI for this game is completely predictable,
with the various insects moving in predetermined patterns, with a small amount of ran-
domness thrown in. Some people would say that the game does not really have any AI.
Indeed, the behaviors of the creatures in the game are exceedingly simple to imple-
ment. But at the same time, the game provides a great deal of challenge for the player.
The difficult part of creating the AI for a game likeCentipedelies entirely in the design
of those creatures’ behaviors and in coming up with the movement patterns that will
provide an interesting challenge for the player. The AI is more design than implementa-
tion.Tetris, perhaps, is an even more extreme example. The only AI the game could be
said to have is the random number generator that determines which piece will drop into
the play-field next. YetTetrisis designed such that this is the only AI the game needs.
The reader may be wondering why I am talking about game AI in a book about
game design. Surely AI is a programming task, and since this book is not about pro-
gramming, the discussion of AI contained in this chapter may seem out of place. But
152 Chapter 9: Artificial Intelligence
If a player plays a game
ofUnreal Tournament
and cannot tell whether
the opponent is a ’bot or
a human, the ’bot’s
artificial intelligence has
passed the Turing test.