[[caption-width-right:196:Toei's version of the [[TitleDrop king of games]]! And HIS TrueCompanions]]

The first Franchise/YuGiOh anime series (also incorrectly known as [[FanNickname Season 0]]) was a 27-episode (and highly [[CompressedAdaptation condensed]]) adaptation of the first seven volumes of the [[Manga/YuGiOh Yu-Gi-Oh! manga]], produced by ToeiAnimation. It loosely covers the story of Yugi completing the Millennium Puzzle up to the Monster World RPG arc of the manga. However, it skips many chapters of the manga in favor of filler episodes and re-introduces a one-shot character from the manga as a main character. Many chapters were reworked to fit the length of an entire episode and a number of the original games were either imported or replaced entirely. It also borrows plot elements that aren't introduced until Duelist Kingdom, such as the early introduction of Shizuka, Jonouchi's sister. Because of its lack of success, this adaptation was cancelled before it got to Duelist Kingdom.

It was eventually replaced by [[Anime/YuGiOh the second anime series]], which preferred to skip all the first parts of the manga [[PlotTumor in favor of focusing only on the Duel Monster arcs and Duel Monster-related filler arcs]]. Nevertheless, the second series [[BroadStrokes does make some nods to this one which can only be fully understood if you've watched it]].

It's a common misconception that this series was "skipped over" by Creator/FourKidsEntertainment's dub for being "too violent". Because the second series was done by a different studio (Creator/StudioGallop) and re-imagined some of the manga chapters that this anime also covered, Toei's Yu-Gi-Oh! is considered an alternate adaptation to it rather than a prequel. For this reason, fans just getting into the series that expect Toei's version to be a prequel to the second series anime will be highly confused by the time they get to [[Anime/YuGiOh Yu-Gi-Oh! Duel Monsters]] (spotting the overlapping plot elements). It's also for this reason that this series was never [[NoExportForYou dubbed]] along with the second series anime, as it's a completely different license and is just as "violent" as the second series anime -- minus the dub censors.

This version contains a different animation-style (utilizing [[ColorWash high contrast colors]]), different character designs ([[AdaptationDyeJob Kaiba has neon green hair]]), a different soundtrack (dark electronic music, as opposed to the orchestral pieces of the second series anime), and contains a different Japanese voice cast.

It's worth noting that some of this series' manga-to-anime alteration practices were carried over by the second studio when producing the second series anime; for example, calling the "Magic & Wizards" card game, as it's known in the Japanese manga, "Duel Monsters". It's also worth noting that this series' incarnation of Seto Kaiba is what inspired the BigBad from a FillerArc of the [[Anime/YuGiOh second anime]], Noah -- whose outfit was somewhat inspired by Kaiba's Death-T outfit from the manga and had green hair, which was a clear ShoutOut to this Kaiba's green hair.

It spawned a 30-minute movie, a few video games and [[TabletopGame/YuGiOhCarddasVersion a card game created by Bandai]], (which would later be replaced as well by [[TabletopGame/YuGiOh the newer card game]] by Konami).

LittleKuriboh is doing an AbridgedSeries of this series as well.

!!"Come... it's trope time!"

* AbandonedWarehouse: The Toei ''Yu-Gi-Oh!'' series gave a warehouse to the yoyo gang, the [[StalkerWithACrush Capumon guy]] and the [[TheKidWithTheRemoteControl guy who plays with 'digital pets']].
* AbusiveParents: Jounouchi's alcoholic father.
* AbortedArc: Because this adaptation was cancelled before it got to the Duelist Kingdom stuff, we never see Toei's version of Kaiba put together the last pieces of his shattered heart, contributing to his HeelFaceTurn in the manga, which turns him into a considerably less psychotic Kaiba like the one we see in the second series.
* AdaptationDyeJob: Kaiba is depicted with bright green hair and yellow eyes, in contrast to his dark brown hair and blue eyes in the manga. It's subverted in the movie where he has near golden-brown hair and light blue eyes, which is closer to his real appearance.
** The school uniforms for the girls are more orange than pink (as they are in the manga), with green bows and skirts instead of blue (from the manga).
** Bakura's hair has a noticeable blue-ish tint to it, and he has green eyes (purple when Dark Bakura takes over), as opposed to his pure white hair and blue eyes (which carries over to Dark Bakura) in the manga.
** Anzu, who had brown hair and blue eyes in the manga and second anime series, has auburn hair and reddish-brown eyes here.
** Shadi's DullEyesOfUnhappiness are amber/light brown as opposed to the dull blue in the anime.
** Aside from the anime-only height difference (which is still less drastic compared to the second anime adaptation), Yugi/Dark Yugi's designs are largely the most manga-faithful designs in this anime. However, Yugi's eye color changes to red whenever he's taken over by Dark Yugi. While the colored manga covers and pages weren't exactly consist consistent with Yugi's eye color, Yugi and Dark Yugi's eyes were never depicted as being a different color from each other.
** Shizuka/Serenity's hair color was brown in the manga. In the anime, she has purple hair.
* AdaptationExpansion: Some of the battles from the manga get stretched out to fill a thirty minute time slot. Case in point, the tenth episode with [[SadistTeacher Ms. Chono.]] In the manga her story takes place entirely in the classroom and solely involves her solving the puzzle Honda left for Miho. In the anime, the puzzle aspect leads to Anzu formally protesting Chono's extreme rules and starts a petition, which Chono then sabotages by using some older students to steal it for her. The shadow game aspect turns into Dark Yugi challenging her to a jigsaw puzzle contest involving mirrors and blindfolds. Chono cheats, and upon completing the puzzle her true, haggish face is revealed. From that point she keeps it hidden with plenty of make-up, but any time she acts unnecessarily strict or mean her face cracks.
* AdaptationPersonalityChange: Hiroto Honda was a completely different character compared to his manga counterpart. In the manga he was a tough guy who was VitriolicBestBuds with Jonouchi, while the original anime series portrayed him as a dorky hall monitor who was obsessed with playing by the rules.
* AdaptationalVillainy: As opposed to the second anime version, this Mokuba is a bit more sadistic. Though he's more tame in comparison to his manga counterpart. In one chapter, he played RussianRoulette via a turning dinner table against Yugi and Jounouchi.
* AlphaBitch: A filler villain named Kaoruko tries to sabotage Anzu and Miho in a popularity contest by sabotaging Anzu's acts, destroying Miho's clothes, and when that doesn't work she ''drugs'' Miho, tears up her clothing, and leaves her in an alley.
* [[AmusementPark Amusement Park Of Doom]]: Death-T.
* AscendedExtra: Miho Nosaka. To elaborate, she was only used in one chapter in the manga as a love interest to Honda (who promptly shot him down when he asked to be her boyfriend). She was used more in the anime to help fill out the girl quota though at best she mostly a SatelliteCharacter. ''[[WebVideo/YuGiOhTheAbridgedSeries Yu-Gi-Oh! Abridged]]'' (when it focuses on the Season 0 series) hilariously lampshades this by hardly having her speak and when she does it a very over the top voice that the other characters bluntly ignore.
* AxCrazy: Dark Yugi can become AxeCrazy [[BullyingADragon if]] [[HeroicBSOD you]] [[BerserkButton get]] [[UnstoppableRage him]] [[RoaringRampageOfRevenge mad]] [[WhatTheHellHero enough.]]
** Dark Bakura.
* BelievingTheirOwnLies: An early PhonyPsychic enemy of the week.
* BewareTheNiceOnes: Ryou Bakura is a very sweet, shy, quiet, polite guy. With a SuperpoweredEvilSide that he's only vaguely aware exists.
** The same goes for Yugi. He is nice and weak, until his psychotic side wakes up.
* BitchInSheepsClothing: Kaiba, he pretends to befriend Yugi and has Yugi's grandfather's Blue Eyes White Dragon switched with a copy. When Yugi figures this out and calls out Kaiba on the switch, Kaiba loses the facade and whacks Yugi in the face with a briefcase.
* BoardGames: Capsule Monster Chess (Capmon). Unlike the manga, it isn't introduced as Mokuba's favorite game until Death-T, instead it's introduced with a filler character in a completely different plotline.
* [[{{Bowdlerise}} Bowdlerization]]: Of the manga (first seven volumes... or at least, what they managed to adapt).
** Much of the death-related Penalty Games being turned into illusions and chapters being either skipped or altered because the content in them was too violent/disturbing (the knife game with Ushio was changed to a game of drawing playing cards). The most notable altered storyline being Death-T, which replaces the chainsaw-wielding Chopman with the more kid-friendly "Game Masters." Kaiba's butler dying from electrocution is also removed, as well as Honda's breast-grabbing perverted baby nephew.
** If you considered the irony between this series and the second anime series, Toei has downplayed the bodycount of character deaths while Studio Gallop's bodycount went very high. Particularly the fourth and final arcs.
* CardGames: Duel Monsters. Plays a large part in all arcs concerning Kaiba.
* {{Catchphrase}}: Yugi has a few.
-->"Come... it's Game Time!"
-->"The door to darkness has opened." (Whenever someone is about to get a Penalty Game)
-->"Game Start!" (A case of import from the manga)
* CharacterDevelopment: Mostly for the two Yugis, but everyone gets a decent amount at the least.
* CherryTapping: How Dark Yugi wins his Penalty Games. Even making a hole in one with a ''stethoscope'' in his Shadow Game with a {{Jerkass}} doctor in episode 16.
* ClockPunk: The Shadow Game between Yugi and a collector/thief of rare watches.
* ColorWash: The first anime has an incredibly supersaturated neon palette.
* ConspicuousCGI: The first series had this a few times (such as in the opening, or in episode 6 with the stairs) and it was quite obvious.
* CompressedAdaptation: Only a handful of chapters from the first seven volumes of the manga were animated along with the anime-original content. In comparison, a lot more chapters from the manga were left out than there were animated, making this anime significantly shorter than the manga even if you don't count Volume 8 onwards.
* CookingDuel: With games.
* TheCorruption: Multiple instances with various characters.
* TheDarkSide: Many characters in Yu-Gi-Oh! fall into some Dark Side's trap, usually by trying to use an {{Artifact Of Doom}} (e.g., Marik, Bakura, Pegasus, Aknadin). Dark Yugi is not immune to this effect.
* DeathTrap: Kaiba's sadistic "amusement park," "Death-T," is basically a long series of increasingly difficult death traps designed to defeat and kill Yugi.
* DemotedToExtra: Inverted. Unlike the second anime, Ryou Bakura is given more screentime even in episodes that correspond to the manga chapters before he was introduced. They don't show anything after Monster World, where he truly becomes part of the main cast, though. Sucks for him.
* TheDitz: Miho.
* DuelsDecideEverything: If you have a conflict, play a game!
* EarlyInstallmentWeirdness: A dark series about a weak and pathetic boy whose darker side wakes up to brutally punish those who inflicted pain to him by using demonic magic ([[MagicPrerequisite which requires a victory in an unspecific game to activate]]) ... it totally sounds like a series about a children's card game.
* EvenEvilHasStandards: Yami Yugi isn't evil per say, but he's not a pure hero either. He does put his foot down when something doesn't sit right with him.
** Yami Yugi may have rigged his mind so that Shadi wouldn't find his true room, but he wasn't about to let the man die.
** When Mokuba is put through Kaiba's brand of "penalty game", Yami Yugi pulls him out before the illusions take full effect on his fragile mind.
*** Oddly enough, in his first manga appearance, Yami Yugi was willingly to put him through a penalty game. Maybe that was his way of putting him in time-out.
* EvilCounterpart: The Millennium Ring/Dark Bakura to the Millennium Puzzle/Dark Yugi.
* [[ExcitedTitleTwoPartEpisodeName Excited Title! Two-part Episode Name!]]: It's a good thing examples don't reference episode names because "Desperate Situation! Passionate Battle for Friendship" and its ilk are keyboard's mouthful. The format varies, but titles usually follow the Excited Exclamation! More Calm Description of Events format.
* EvilSoundsDeep: Played straight with Yugi -> Dark Yugi and Bakura -> Dark Bakura.
* FightingSeries: Using games. Though Jonouchi plays a live-action fighting game during Death-T using Power Suits.
* GeckoEnding: This anime ended at the Monster World arc and never got around to doing any other chapters. Kind of had it coming for skipping tons and tons of episodic chapters that could have served as padding and an alternative for filler.
* GottaCatchEmAll: In the first series anime, Yugi's Grandpa said that Capsule Monsters was not a collection game, but the epitome of a fighting game. Dark Yugi later echoed this in delivering his LaserGuidedKarma.
** Depends on which version of Bakura from which version of the anime ([[Manga/YuGiOh or manga]]) you ask, though collecting them all is still featured prominently either way. Also in the manga and first anime series, when he would collect the souls of his victims into miniatures.
* GracefulLoser: Aileen Rao.
* KillerGameMaster: Dark Bakura. Tabletop {{Role Playing Game}}s are supposed to be adventurous, not scary!
* KingOfGames: TropeNamer; it's the title the main protagonist has for his mastery of gaming.
* LighterAndSofter: Compared to the manga.
* TheManBehindTheMan: In the virtual pet episode, it's revealed that the timid Haiyama boy that Yugi befriended before was ''controlling'' the large Kujimoro guy. What's worse was that he was treating him ''like a pet''. Talk about a plot twist.
* MindRape: The Penalty Games. Moreso here than the manga because most of the manga's death Penalty Games were replaced with illusions.
* MundaneMadeAwesome: Those yo-yos, man. Those yo-yos.
* NonSerialMovie: Toei's 30 minute movie made after the cancellation of the anime. It features the same voice actors that appeared in this series and features the same songs, but the character designs are more accurate to the manga (Kaiba has brown hair, and his personality/wardrobe is similar to his mid-Duelist Kingdom manga appearance). Not to mention, the plot aspects of this movie are rather contradictory to its own anime. Bakura isn't present, Kaiba seems to be relatively "normal" and awake even though he's supposed to be suffering from the aftereffects of Mind Crush and in a coma, Yugi and Kaiba use the first version of the Duel Disks which aren't introduced at this point, etc. It could take place after this anime's equivalent of Duelist Kingdom [[CrypticBackgroundReference that never aired]], but Jonouchi doesn't recognize the Red-Eyes Black Dragon (it's treated as some legendary card) and Saruwatari still works for Kaiba, although Toei's adaptation of ''Manga/YuGiOh'' has always been rather weird, so who knows?
* OhCrap: Default reaction to Dark Yugi's Shadow Game victims. Dark Bakura has an OhCrap moment when he realizes the real Bakura regained control of his left hand.
* TheOnlyOneAllowedToDefeatYou: To the point where Kaiba stalks Yugi for an entire episode because he suspects someone ''else'' is trying to defeat him in a duel.
* RealityWarper: A major difference between this and the manga/second series anime is that the Puzzle seems to give Dark Yugi reality-warping powers. In contrast to the manga where Dark Yugi challenges Ushio to a knife game on the spot, Dark Yugi in this anime transports Ushio (by surprise, who was walking home) to a tower, tied to a rope which appears out of nowhere. Dark Yugi also seems to make the [[ArtisticLicensePhysics playing cards stay in place on the wall]]. And in the "watch thief" episode, he transports the watch to a dimension of clock gears and in general can conjure up anything needed for his Shadow Games.
* RedEyesTakeWarning: Dark Yugi has red eyes in this series and this is played straight for anyone who harms Yugi.
* SparedByTheAdaptation: Most of the characters in the anime are spared from their particularly nasty demises, especially Prisoner 777 who was ''burned alive'' in the manga was given a MindRape Penalty Game.
* StalkerWithACrush: Warashibe seemed to be this for Miho. However, his strange obsession with Capumon and her merged and he became a {{Yandere}}, determined to claim her by any means necessary.
* StalkerWithoutACrush: As stated before, Kaiba is so determined to beat Yugi that he follows him around town, waiting to jump him.
* TwoGirlsToATeam: Due to Miho being upgraded to a main character from her one-off status in the manga, she and Anzu are the main female characters.
--> ''"[[Music/TheyMightBeGiants Make a little birdhouse]] [[Creator/LittleKuriboh in your soul.]]"''