The ghosts in the original Pac-Man had unique AI traits, which was the least predictable?

In the original Pac-Man (released in October 1980 as an arcade game in Japan), the ghosts, also known as the "Ghost Gang," each had unique AI traits that contributed to the game's enduring appeal. These four ghosts – Blinky, Pinky, Inky, and Clyde – were programmed with distinct behaviors to challenge players in different ways. Their varied strategies ensured that no two games felt exactly the same, making Pac-Man both engaging and unpredictable.

Also see: 50 Years of Video Games

The ghosts were described in Japanese as having the following character personalities:

• Blinky (the red ghost), nicknamed "Oikake" in Japanese, meaning "Chaser," was programmed to relentlessly pursue Pac-Man. Once Pac-Man eats a certain number of pellets, Blinky speeds up and becomes even more aggressive, earning him the secondary title "Cruise Elroy" in later stages. His behavior was the most direct and consistent, making him the easiest ghost to anticipate.
• Pinky (the pink ghost), called "Machibuse" or "Ambusher," was designed to position herself ahead of Pac-Man's movements. Instead of chasing Pac-Man directly, Pinky attempts to intercept him by targeting a point four tiles ahead of his current direction. This makes Pinky's strategy more tactical, especially when Pac-Man is navigating corners or tight areas.
• Inky (the blue ghost), known as "Kimagure," which translates to "Fickle," had the most unpredictable behavior. His AI combines both Blinky's targeting system and Clyde's wandering tendencies. Specifically, Inky's target is determined using a complex formula that considers both Pac-Man's position and Blinky's position, which results in erratic movement patterns.
• Clyde (the orange ghost), referred to as "Otoboke" or "Feigned Ignorance," exhibits dual behavior. At times, he mimics Blinky by chasing Pac-Man, but when he gets too close to him, Clyde switches to a more passive, wandering mode. This odd mix of aggression and aloofness adds an element of surprise to his behavior.

These AI traits were groundbreaking for the time, as they allowed each ghost to feel like a distinct character rather than a simple enemy. Among these, Inky's behavior stands out as the most complex and least predictable. His use of both Pac-Man's and Blinky's positions to calculate his target introduces an element of chaos to the game.

For players, this often made Inky the most challenging ghost to avoid, as his erratic behavior could disrupt even the most carefully planned strategies.