The highest normally reachable numbered level in Namco’s 1980 arcade game Pac-Man is level 255.
Pac-Man’s original arcade program contains 255 playable maze levels before its well-known split-screen or kill-screen stage. On level 256, a programming overflow corrupts the right side of the maze, producing a mixture of garbled symbols, colored blocks, and incomplete level elements. Because the stage cannot be completed normally, level 255 is generally treated as the final properly playable level.
The overflow happens because the game’s fruit or level counter was designed around an 8-bit value. When the game attempts to advance beyond its intended range, the display data on the right side is affected. The issue became one of the most famous technical quirks in arcade history.
People sometimes answer “level 256” because that is the famous kill screen. However, level 256 is the corrupted stage itself; level 255 is the last complete maze that can normally be finished.