He began officially supplying verified video game scores to Guinness World Records in 1983. Walter Day has appeared in several documentaries including Icons, Chasing Ghosts: Beyond the Arcade, The King of Kong: A Fistful of Quarters, Coin-Op TV, Frag, E3 ‘09 Live, King of Con!, The Perfect Fraudman, The Video Craze, Gamer Age, The King of Arcades, Man vs Snake: The Long and Twisted Tale of Nibbler, Easy to Learn, Hard to Master: The Fate of Atari, Rocksteppy, and more. Day is said to be the inspiration for the character Mr. Litwak in the film Wreck-It Ralph.