Pac-Man 8-Bit AI Pac-Man is the most famous arcade video game of all time. It was created in 1980 by Japanese video game designer Toru Iwatani for Namco. In Japanese the game is Pakkuman from the Japanese word paku, meaning “chomp”. Pac-Man’s shape resembles a pizza missing a slice, or a simplifyed Kanji character for mouth, kuchi.

By 1982, Pac-Man sold 400,000 copies worldwide played by over 30 million players. Pac-Man created a new game genre, the maze chase, at a time when popular video games were space shooters like Space Invaders, Millipede and Asteroids.

Ghostly Personality Pinky When Pac-Man was programmed, computers had limited power and storage. There are 256 levels because the level is stored in a single 8-bit register. The game is drawn with the few colors and block drawings allowed by 1980’s technology. In order to make the game play fast, the designer needed simple rules for the movement of each of the “ghosts”; the algorithms require few com- Blinky putations but still make the game challenging. Cly de Each ghost moves based on Pac-Man’s position in the Inky shortest path: - “Blinky” always chases Pac-Man, targeting the same spot Pac-Man occupies. - “Pinky” targets two dots in front of Pac-Man to ambush him. - “Inky” aims for a spot equidistant from two dots in front of Pac-Man to Blinky’s current position but in the opposite direction. - When “Clyde” is farther than 8 tiles from Pac-Man, it chases like Blinky. When Clyde closes to fewer than 8 tiles he suddenly retreats to the lower-left corner of the maze in a shy feint and retreat. The ghost’s Japanese name translates to “Feigned Ignorance.”

These kinds of movement algorithms are actually an early form of artificial intelli- gence. The ruleset is surprisingly similar to those used to drive Roomba vaccuums around your living room. The Prof. Asks? 1. What strategies could you employ to avoid one or more of the ghosts? In par- ticular, what is a good way to avoid Pinky? 2. Play a few rounds of Pac-man. What other game features are used to make the ghost behavior more interesting? Which would you add and how would you rexpress it as math using x-y coordinates?

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