For those not in the know, computer controlled Civs would be assigned behaviour attributes based on historical personality. Each attribute would be 1-10, stored in an 8 bit integer.
These attributes change in response to events in the game. When a civilization would reach the modern era, it's aggression attribute would be reduced by 2. Gandhi's aggression was reduced from 1 to 255 (underflow). He would rain down nukes on everything in sight, somewhat uncharacteristic of him.
Fans liked this so much that Firaxis maintained the same behaviour in later games.
