He achieved fame throughout the 1980s and 1990s by claiming numerous records on classic video games, including a perfect score on Pac-Man.

[5] He was initially uninterested in video games, but as they became more popular, according to Mitchell, "[e]veryone was standing around the Donkey Kong machine and I wanted that attention".

In November 1982, Life brought several notable arcade players, including Mitchell and Sanders, to Ottumwa for a photoshoot.

[5] Later, Sanders admitted that he had lied about his previous Donkey Kong scores, and Twin Galaxies gave the record to Billy Mitchell who held it for more than 18 years.

[13] Around this time, Mitchell established a friendship with Robert Childs, who had a business buying and installing arcade cabinets in places such as laundromats.

[5] Later that summer, Day founded the US National Video Game Team, a slimmer version of the Electronic Circus, which aimed to stop in a major city in each US state; but the inaugural event encountered many snags.

Following a 1982 claim made by an eight-year-old player of reaching more than 6 million points, which gained national coverage after President Ronald Reagan wrote to congratulate the player,[2] 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.

[14] In 2004, Mitchell achieved a Donkey Kong score of 933,900, in front of multiple witnesses at the Midwest Gaming Classic, his new personal best.

Wiebe attempted to have Mitchell present at these events to challenge him directly, typically at Funspot arcades, as public demonstrations of high scores were preferred over video tapes.

"[6] Mitchell failed to appear at Wiebe's events, saying he had not played games for half a year and needed to retrain and practice for the competition.

[16] During Wiebe's attempts, he achieved a score of more than one million points on an arcade unit at his home, which was recorded on videotape and initially accepted by Twin Galaxies but later retracted, since Wiebe's unit used an unofficial "Double Donkey Board" that had circuitry for both Donkey Kong and Donkey Kong Jr. Later in his attempts, Wiebe again managed a high score in front of multiple witnesses at a New Hampshire Funspot, which Twin Galaxies accepted.

[27] In 2015, Mitchell filed a lawsuit against Cartoon Network, saying that in the series Regular Show, a character named Garrett Bobby Ferguson (GBF) who cheats at video games infringed on his likeness.

[29][30] In August 2017, Jeremy Young, a moderator of the Donkey Kong Forum, expressed concern related to a video posted online by Childs of Mitchell's score at Boomers.

The videos did not show the complete record-breaking runs, and Young believed there might have been issues with the board swap.

[5] Young subsequently removed the three scores from the Donkey Kong Forum website for misrepresenting MAME emulation as authentic gameplay.

[15] Mitchell defended his scores on the East Side Dave Show shortly after this charge, saying: "I've never even played MAME.

[32] Young responded, "The amount of foresight, patience, and technical knowledge required would be staggering" to make such tapes.

[31] To support his case, Mitchell said he sent Twin Galaxies recordings of the gameplay from these high-score efforts along with other secondary evidence to refute charges of cheating.

[34][35] Subsequently, Guinness World Records released a statement that it would remove Mitchell's scores: "The Guinness World Records titles relating to Mr. Mitchell's highest scores on Donkey Kong have all been disqualified due to Twin Galaxies being our source of verification for these achievements."

[5] In early 2019, Mitchell filed lawsuits against Twin Galaxies as well as Young and YouTuber Apollo Legend.

[43] In September 2022, forensic analyst Tanner Fokkens and five other experts published a report finding that, after technical analysis of his gameplay, Mitchell could not have obtained his records on original arcade hardware, the stage-to-stage transitions being consistent with those in MAME.