When Namco designer Toru Iwatani released Puck Man (later renamed Pac-Man for Western release) in 1980, the arcade space was almost completely dominated by space shooters such as Space Invaders and Asteroids. Iwatani consciously set out to create a title that appealed to non-violent sensibilities, focusing on colorful characters, eating mechanics, and comical intermissions.
The Four Ghosts & Behavioral AI Algorithms
What made Pac-Man infinitely playable was that each ghost (Monsters) was programmed with a unique movement AI target tile routine. Rather than random wandering, every ghost shifted between Chase, Scatter, and Frightened state machines.
| Ghost Name | Japanese Name | Targeting Algorithm / Personality |
|---|---|---|
| Blinky (Red) | Oikake (Pursuer) | Directly targets Pac-Man's exact tile coordinates. Increases speed as dots decrease ("El Robo"). |
| Pinky (Pink) | Machibito (Ambusher) | Targets four tiles ahead of Pac-Man's current facing direction to block escape routes. |
| Inky (Cyan) | Kimagure (Fickle) | Calculates vector reflection off Blinky's location to create chaotic sandwich movements. |
| Clyde (Orange) | Otoko (Coward) | Chases Pac-Man when farther than 8 tiles away; retreats to bottom-left corner when closer. |
Hardware Limits & The Level 256 Split-Screen Bug
The original arcade board ran on a Zilog Z80 CPU operating at 3.072 MHz with 2 KB of RAM and custom tilemap video chips. Because game values were stored in 8-bit unsigned integers, the sub-routine responsible for calculating fruit bonuses at level 256 caused an integer overflow error.
This overflow corrupted the right half of the maze buffer with random ASCII character tiles and fruit sprites, rendering Level 256 unwinnable and defining the concept of the perfect 3,333,360 score limit.