characters move around in a town more or less “realistically.” In a game likeThe Sims,
the AI more or less is the game; with weak AI the game would simply not be worth
playing.
So different games provoke different expectations in players of how smart the AI
agents in those games need to be. However, we can still construct a general list of goals
for any computer game AI, goals that change in importance as the design goals for a
given game vary.
Challenge the Player...........................
Providing a reasonable challenge for players must be the primary goal for AI in any
computer game. Without setting up a worthy adversary of some sort, a game becomes
unchallenging and therefore too easy to defeat. Worse still, a game that provides no
dynamic challenge stops being a game entirely and becomes more of a puzzle or an
interactive movie.
In a classic arcade game likeRobotron: 2084or in a first-person shooter likeDoom,
the challenge mostly comes from players being overwhelmed by adversaries and by the
powerful abilities those adversaries have. For instance, in my oft-used example ofCen-
tipede, the bugs can kill players by touching them, while players must shoot the
creatures in order to kill them. This puts players at something of a disadvantage. The
fact that there are multiple insects attacking players at once does not help matters. As a
result, the AI for these creatures can be fairly simple and predictable, yet players are
still challenged by them.
The same imbalance holds true inDoom, where players may run out of ammo but
their enemies never do, where players are much more helpless in the dark while the
enemies can detect players just as easily as in the light, and where often the enemies,
such as flying creatures, can go where players cannot. The fact that the creatures far
outnumber the player character also tends to compensate for the reality that none of
the creatures is very smart. The AI inDoomhas to appear more sophisticated than the
Centipedeinsects because theDoomworld seems more real than theCentipedeworld,
as I will discuss in a bit. The fact remains that primarily the AI provides a challenge for
154 Chapter 9: Artificial Intelligence
In a classic arcade game like
Robotron: 2084, the challenge
comes from the sheer number of
opponents the player must fight.