Game Development Reference
The research showed these emotions link to the following four different ways of
having fun [Lazzaro07]. It should hardly be a surprise that the most popular titles
incorporate at least three of the four.
n Hard fun: The fun of succeeding at something difficult
n Easy fun: The fun of undirected play in a sandbox
n Serious fun: ''Games as therapy'': fun with a purpose
n People fun: The fun of doing something with others
Game designers must be fluent in these areas, and AI programmers should at
least be familiar with them. The AI will be tasked with supporting these kinds of
fun and evoking these emotions in the players. When designers ask for some
''good AI,'' the AI programmer should ask if they mean ''hard to beat'' or ''fun to
play with'' or something altogether different. In order for AI programmers to
implement a good AI, they have to implement the right AI. Let us consider the
many ways such an AI can express itself.
Musicians will tell you that half the emotional content of a film is in the musical
score. Music is a powerful tool for evoking a full range of responses in the player.
Games have incorporated it since shortly after the first PC sound cards became
available. Unlike films, games can exhibit a fluid control over their music and
change it in response to player actions. Games can do more than pick what music
fits a scene. Back in 1990, the game Wing Commander not only made smooth
transitions in the music every two to four bars on beat boundaries, but it also
transitioned instantly when there was a serious change in the game state, such as a
missile chasing the player [Sanger93].
Something has to decide what to play and when. That something is just another
form of AI with new outputs. At its simplest, music follows a fixed script with no
changes based on player interaction. The designer says, ''This is the music I want
for this level.'' If the designer wants more out of the game, he or she will want
player interaction to drive as much of the experience as possible. Interaction is
the key differentiator between games and other media. ''I need this game to react
to what the player does and do something appropriate'' are the marching orders
for the AI, whether it is doing resource allocation in a strategy game or music
selection in a flight simulator.