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 the 8-bit byte distinct values. As a result, the final board is unplayable, with the right half replaced by a series of garbled symbols and letters.
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 8-bit byte, and could therefore store only 256 distinct values because in binary, the highest number you can store with 8 1s is 255, add 1 and it becomes 0000000 or 0. Players who reached the 256th board would in fact overflow this counter and end up playing board zero — something the fruit counter's logic was not designed to handle. The fruit counter said "Okay, take the level number, and subtract one and then draw a fruit. Now is the level number zero? If no, repeat. If yes, start." The problem is, 0 - 1 = 255. So 256 fruits are drawn. Causing the drawing routine to show glitch symbols since it is trying to take other data as graphics. The final board was unbeatable, with the right half replaced by a series of garbled symbols and letters. With most of the dots are gone, the game still thinks "Okay, the number of dots pac-man ate isn't enough, keep going." (directly from Wikipedia and other sites).
At the end of the credits of the movie Wreck-It Ralph is shown the castle of Disney but with the error of the screen of the last level of Pac-Man.