Pac-Man has a bug in it that prevents it from being completely finished. This bug occurs at the 256th board, where it will cause an overflow in the 8-bit byte distinct values. As a result, the final board is almost unplayable, with the right half replaced by a series of scrambled symbols, garbage tiles, and letters.
How does this glitch occur?Edit
It's extremely hard to do this glitch unless you have extreme patience and dedication. You have to play up to the 256th board, which can take up to 6 hours of non-stop playing. You can also use an emulator and skip to it.
Why does this exist?Edit
While probably not the first game to suffer from a kill screen, Pac-Man's is possibly the most famous. Pac-Man's level counter was a single byte, and could therefore store only 256 distinct values (0-255). Players who reached the 256th board would cause a buffer overflow, causing the data in other areas of the stack to be overwritten. The final board was unbeatable, with the right half replaced by a series of random symbols and letters.
How can I prevent this from happening in my arcade cabinet? Edit
You can't with normal arcade machine versions. Some versions, however, have a board reset after completing the 255th board, meaning the player will start again at the first board with the score staying the same as before the reset. This allows the player to continue with the game without encountering the bug. Donhodges.com has a fix for the glitch. If the player somehow manages to beat level 256, they will return to level 1, as the game reads level 256 as level 0. Some tiles will act like walls.
So what does this mean for me? Edit
- It means you can only get about 3,333,360 points (Current world record by Billy Mitchell). It means you can't play this game forever. However, as of 04/12/2018, Billy Michells record has been removed and disqualified for falsifying the score with an emulator. Thus, no longer holding the world record anymore nor in the future as he has been permanently banned/disqualified from submitting high scores.