Game Development Dictionary
The player directed Pacman through the maze. The maze was strewn with pellets, and when Pacman came into contact with one of these pellets, he would eat it. The game level would be completed when Pacman had gobbled up all the pellets in the maze. (This ensured that Pacman had been virtually everywhere in the maze at least once.)
The four ghosts would pursue Pacman through the maze. And if they caught him, he would die. When Pacman had died three times, the game would be over. (The player could earn extra lives by reaching certain scores during the game.) So the player would have to direct Pacman through the maze, avoiding the ghosts, and eating up all the pellets.
To help the player out, each maze featured four "power pellets". When Pacman ate one of these, he would gain the ability to eat the ghosts. This power only lasted for a brief time. But this added a wonderful element of strategy to the game.
Another nice feature was the presence of "side exits". These were openings on the side of each maze. When Pacman went out through one of these exits, he would reenter the maze through its corresponding exit on the other side of the screen. In other words, if Pacman went out one of the side exits on the left, he would reappear on the right side of the screen.
This often helped Pacman to avoid the ghosts. But the ghosts could also use the side exits. However, it seemed that the ghosts traveled through the side exits more slowly than Pacman did.
Pacman also featured very nice artificial intelligence programming. Each of the four ghosts actually followed a different strategy when pursuing Pacman. One followed him, one attempted to head him off by taking alternate routes through the maze, one stayed toward the center of the maze, and the fourth, who was a nice fellow (ut-bay ot-nay oo-tay ight-bray,) just sort of wandered about.