14There Was Another Series Of The Anime (That We Never Saw)
The Yu-Gi-Oh! anime that most fans are familiar with is actually called Yu-Gi-Oh! Duel Monsters in Japan, and it was the second series to be produced. The first Yu-Gi-Oh! anime (sometimes referred to as "season zero" by fans) was produced by Toei Animation, and ran for a single season in 1998.
What we now know as the Yu-Gi-Oh! card
game did not appear until later episodes, where it was called Magic and Wizards, and was in a much more primitive form. The anime followed the story of the original manga, with the much darker version of the Pharaoh (and his murderous antics). Early versions of characters like Kaiba and Bakura also appeared in this series. This season of the anime had its own film, called Yu-Gi-Oh! The Movie. The character designs in the film more closely resembled the ones seen later in the Duel Monsters version of the anime.
By the time the next season of the anime was released (the one that was released in America), the Duel Monsters card game had been fleshed out. It became the central focus of the story, and was entwined with the story of the Millennium Items.