Mitchell worked with his friend Chris Ayra in 1983 to determine that the highest possible score on Pac-Man was 3,333,360, which would require a perfect no-death run and collecting all possible points on the nonsense side of level 256's split-screen, requiring knowledge of where the edible dots were.
In 1999, a group of Canadian players, including Rick Fothergill, were reportedly close to reaching the theoretical high score, leading Mitchell to return to video gaming to try to beat this group to the achievement. On May 8, 1999, Fothergill set the world record, just 90 points short of a perfect score. In response, on July 3, Mitchell achieved the perfect score at an arcade in Laconia, New Hampshire, and set the game's world record as recorded by Funspot and Twin Galaxies.