A brief explanation why…
As one of the more iconic bugs in gaming history, reaching level 256 in the Pac-Man arcade game would cause half of the screen to be rendered in a jumbled mess. The left of the screen would appear as expected while the right displayed a mixture of random characters.
The bug stems from a memory overflow error in the code that retrieves the number of fruits shown on the bottom right of the screen and there's only enough memory to draw half the board.
Because there's no possible way for Pac-Man to eat the number of dots required to pass the level, the "split screen" bug effectively marks the end of the game, forcing you to take a loss with no congratulatory message or credit roll.
Toru Iwatani, the creator of Pac-Man, never intended for there to be an end to the game.