Pac-Man level 256: the kill screen explained
After 255 flawless boards the maze tears itself in half. The cause is one byte of memory, and the result is the most famous bug in arcade history.
What the player sees
Board 256 starts normally on the left side of the screen. The right side is replaced by a jumble of letters, numbers, fruit icons and fragments of other graphics. Dots are scattered through the garbage, a few of them edible, most of them not. Because the board cannot be completed, the ghosts simply continue until all lives are gone. Players call it the split screen or the kill screen.
Why it happens
- The game stores the level number in a single byte, which can hold values 0 to 255.
- At the start of each board the fruit-counter routine draws the icons for the current level and the six before it in the bottom corner. For levels above seven it draws the last seven; for the first seven it draws all of them.
- On board 256 the counter wraps to 0. The routine reads this as a level with no entries to skip and begins drawing from a table with a length of 256, iterating a byte-sized counter that never reaches its stopping condition.
- It writes 256 entries, far more than the seven slots at the bottom, straight across video memory, overwriting the right half of the maze with whatever the table pointer happens to be reading from.
Nothing is damaged permanently; the next game starts cleanly. The same class of bug, an 8-bit overflow, ends Donkey Kong at level 22 and Dig Dug at round 256.
Why it was never caught
Reaching board 256 requires roughly three hours of perfect play on a 1980 cabinet. Namco's testers never played that far and had no reason to expect anyone would. The glitch was discovered by players in the arcades, documented by the early high-score communities and eventually incorporated into the definition of a perfect game, explained in how a perfect pacman game works.
What a perfect game does with level 256
The handful of dots that remain reachable on the broken board can still be eaten, and they are counted in the perfect-score total of 3,333,360. A player on a perfect run eats everything available, then deliberately loses the remaining lives, because there is no way to proceed. Fastest-completion records measure the time to that point; see pacman world records.
Fixes and homages
- Fan-made ROM patches extend the counter to 16 bits, allowing play past 256 with the normal difficulty of level 21 onward.
- Bandai Namco embraced the bug: Pac-Man 256 (2015) turns the glitch into a wall of static that chases the player up an endless maze. See pacman 256 compared to pacman 99.
- Pac-Man Championship Edition removed level counters entirely by making the game timed.
Could the original have avoided it?
Trivially: a single bounds check in the fruit routine. But every byte mattered, and the engineers were optimising for a game expected to last a few minutes per credit, not for players who would spend decades learning it. That gap between design intent and player dedication is part of what makes the game's history, told in the complete history of pacman, so compelling. The games on the mr pacman retro arcade hub have no level limit, in tribute.
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Frequently asked questions
What happens at level 256 in Pac-Man?
The right half of the maze is overwritten with garbage graphics and the board cannot be cleared, ending the game.
Why does Pac-Man end at level 256?
The level counter is a single byte that overflows to zero, which breaks the routine that draws the fruit indicator.
Is level 256 the last level?
Effectively yes. Board 255 is the last normal board.
Can you beat level 256?
No. Too many dots are unreachable, so the board can never be completed.
Did Namco fix the bug?
Not in the original; later releases and fan patches change the counter or remove levels altogether.