What is the term for the glitch on Pac-Man's 256th level?

The glitch on Pac-Man’s 256th level is called the kill screen. It is a hardware and software error that makes the right side of the maze display incorrectly, preventing the level from being completed normally.

The problem results from an integer overflow in the original arcade game. Pac-Man was designed to progress through 255 regular levels, but when the game attempts to load level 256, part of the level data is interpreted incorrectly. The left side of the screen remains playable, while the right side becomes a scrambled mixture of maze tiles and colored blocks.

The kill screen became one of arcade gaming’s most famous technical limitations because it marks the practical end of a perfect run. Skilled players can reach it after clearing the first 255 levels, but they cannot finish the 256th maze through ordinary play. The term is sometimes confused with “game over,” but a game over means the player has lost all lives; the kill screen specifically describes the broken 256th level. Pac-Man’s documented perfect score is 3,333,360 points.