AI in Games, Part 2 - Pac-Man and AI

Okay, let's skip the pointless drivel and talk about important things...

The first exposure I had to AI was in Pac-Man. Yes, Pac-Man.

The ghosts behaved differently and independent of one another, from the player's perspective. In part one we talked about how there's only one computer, so think of the ghosts as the computer's fingers. The computer controls each one in a specific way, and though they be separate, they are connected by the fact that there is only one hand controlling them.

According to Jamey Pittman, the ghosts have three modes of operation: Chase, Scatter, and Frightened. This is their behavior that can be understood by the player and reacted to appropriately. The player will also learn that Pac-Man can do somethings they can't: fast cornering and reversing direction. The ghosts can't change direction except when they change modes, like going from Frightened to Chase.

Each ghost has their own individual behavior as well:

• Blinky (Red) pursues Pac-Man relentlessly. His AI is programmed to target Pac-Man, wherever he be.
• Pinky (Pink) targets the tile four spots ahead of the direction Pac-Man is moving. This is why people always complain that he ambushed them. 
• Inky (Blue) is erratic. He sometimes targets Pac-Man, other times he moves in odd ways, and sometimes targets an area near Pac-Man. 
• Clyde (Orange) changes his behavior. Sometimes he targets Pac-Man, but when he gets close, he retreats away from him. This makes him somewhat unpredictable.

These four give insights, not only into Pac-Man, but into video games as well. They can teach that four distinct characters need four distinct behaviors. This allows the player some challenge, while at the same time allows the player to find a ghost he or she "hates".

I know I always hated the red one. Now I know I was supposed to hate the red one.

Developers, think about a character behavior you are trying to design. Consider examples from Pac-Man for your thought processes, and ask:

Who do I want the players to hate?
Who do I want them to feel sorry for, and why?