up such that he is the most effective combat companion in the game, enabling him to
help players dispatch the countless creatures that keep rearing their ugly heads.
Of course, there is a wide range of different effects that can be achieved using the
game’s AI to create interesting interpersonal relationships. Sadly, this is something
that has been all but unexplored in commercial games to date. Instead of telling static
stories, we could be telling ones that, though not entirely procedurally generated, were
subtly different depending on how players played the game. Using AI to spice up and
vary the story from game to game may make telling a story much more difficult, but
what it can add to the game’s non-linearity and replayability is enormous.
Create a Living World..........................
In many games, the AI does more than just provide a threat and a challenge to the
player. A game may even include AI agents that players do not directly interact with at
all. The AI can instead be used to inhabit the living world the game creates. A
game-world may be infinitely detailed in terms of the objects it contains and how it
looks and sounds, but players are used to a real-world that also contains living organ-
isms that think for themselves and behave in interesting ways. Therefore, creating a
sterile game-world filled with inanimate objects is not going to be a very believable
space for the player. One does not need to go overboard in filling up the game-world
with complex ambient AI agents; a little can go a long way. Whether this means a few
birds that fly around in the sky, insects that crawl around on the ground, or humans that
go about their daily business, adding ambient life to a world can do a lot to make the
game-world seem more real to the player. TheGrand Theft Autogames have featured
cities full of humans going about their daily lives, most of whom are not directly needed
for the main story. These pedestrians make the city seem more real, and the more real
the game-world is the more likely that players will be able to immerse themselves in it.
There is a close connection between filling the game with ambient life and using
the AI to tell the game’s story. Creating these inhabitants does a lot to establish the set-
ting for your game, and setting is a key part of telling any story. But ambient life in a
game goes beyond just establishing that setting; it helps make players feel less lonely in
the game-world. How many times have you played a game where you felt like you were
walking around a sterile wasteland, as if an exterminator had come through previously
to eliminate any signs of life? Players love to see that the world has ambient life in it,
creatures they can just look at rather than kill, and the depth it adds to the world can be
invaluable.
The Sloped Playing Field..........................
Often when programmers get together to talk about AI for computer games, they con-
centrate their discussions on how they want their AI agents to be on equal footing with
the player. This was certainly the case at the AI roundtables I have attended in years
past at the Game Developers Conference. These AI specialists want their AI systems
to know only what players would know, see what players can see, and so forth. This,
they suggest, will make the conflict between the AI and players more realistic and
therefore more interesting.
162 Chapter 9: Artificial Intelligence