In 1984, the game ''Hydlide'' came out on the Japanese microcomputers PC-6001 and PC-8801. Upon its release in UsefulNotes/{{Japan}}, it was hailed as a revolutionary title. It was one of the first ever games in the emerging {{Action RPG}} genre, was the UrExample of a fully-scaled WideOpenSandbox world, and even introduced the RegeneratingHealth mechanic. The game's success led to ports across multiple other Japanese computer systems, and eventually the [[UsefulNotes/NintendoEntertainmentSystem Famicom]] console in 1986, selling 2 million copies in Japan. Its revolutionary game design had a big influence on later action RPG franchises such as ''Franchise/TheLegendOfZelda'' and ''Franchise/{{Ys}}.'' However, ''Hydlide'' was not released in North America until 1989, when North American gamers played the 1986 Famicom version for the first time on the NES. It is this version that the majority of UsefulNotes/{{North America}}n gamers know about.

A princess is attacked by the demon Varalys, who breaks her into three fairies and scatters them through the land. One of her kingdom's bravest knights, Jim, sets out to retrieve the fairies and the crystals that will restore her to her original form and allow him to slay Varalys.

While the original microcomputer versions sold well in Japan, the NES port later gained notoriety in North America for being [[SeinfeldIsUnfunny terribly outdated]] in comparison to later, more refined, superior action RPG titles like ''Franchise/TheLegendOfZelda'' and ''Franchise/{{Ys}}''. Compared to those games, the graphics in ''Hydlide'' looked "messy and hard to interpret" in comparison. Unaware of when ''Hydlide'' first came out, some North Americans even wrongly accused ''Hydlide'' of being "a badly designed ripoff" of either ''The Legend of Zelda'' or ''Ys'', when in reality, it was actually the other way around: both ''The Legend of Zelda'' or ''Ys'' were heavily influenced by ''Hydlide'' in the first place. This makes ''Hydlide'' a classic example of the SeinfeldIsUnfunny trope, with later generations failing to realize just how revolutionary it was for its time.

The game received several sequels, including ''Hydlide II'' for the PC-8801 and {{UsefulNotes/MSX}} in 1985, ''Super Hydlide'' (''Hydlide 3'' in Japan) for the MSX and PC-8801 computers in 1987 and Sega Mega Drive[=/=]UsefulNotes/SegaGenesis console in 1989. It was also remade as ''VideoGame/VirtualHydlide'' for the UsefulNotes/SegaSaturn in 1995. While ''Hydlide II'' and ''Super Hydlide'', with innovations such as a MoralityMeter and [[InUniverseGameClock Day Night Cycle]], were considered good games in Japan, they became very outdated by the time ''Super Hydlide'' released in North America in 1990.

For clarity purposes, the original (or the Famicom/NES version) will be just called ''Hydlide'', ''Hydlide II'' as ''[[ShapedLikeItself Hydlide II]]'', and ''Super Hydlide'' as ''Super''.
!!This game contains examples of:
* {{Action RPG}}: This was one of the first ever games in the Action RPG genre, along with ''VideoGame/DragonSlayer''.
* AerithAndBob: In a world containing the likes of Varalys and Kaizack, our hero is simply named ''Jim''.
* AWinnerIsYou: When you beat the game, you get a text "Congratulations!" While the player and the princess (you saved) just stand there doing their Idle animations, it then goes to the title screen.
* BigBad: Varalys, the final boss of the original. He's [[DemotedToDragon reduced to the Dragon]] in ''Hydlide II'' and ''Super'', with a dark crystal in the latter and Kaizack in the latter taking the role of Big Bad.
* GenreShift: ''Super'' takes a hard left turn into science fiction around the halfway point.
* GuideDangIt: There is absolutely ''no'' clue at any point what you're supposed to do.
* JokeItem: The Sega Pack in Super Hydlide. It even says "It's a joke." when you try to use it.
* KnightInShiningArmor: Jim.
* MindScrew: ''Super'' goes all the way in the second half of the game, where you're in space fighting robots and finding computer data, not to mention the final battle where it's revealed that the game's BigBad is in the fact the creator of the entire universe!
* MoneySpider: Played straight in ''Super''.
* MoralityMeter: ''Hydlide II'' was one of the first ever games to feature this mechanic. The game introduced a morality meter where the player can be aligned with Justice, Normal, or Evil. Killing humans or good monsters lowers the player's morality, while fighting evil monsters increases it. If the player has an evil alignment, the townsfolk will ignore the player, denying access to certain clues, dialogues, equipment, and training.
* RegeneratingHealth: The original ''Hydlide'' was an UrExample of this trope. It introduced a health regeneration mechanic where health and magic slowly regenerate when standing still. It inspired the regenerating health mechanic in the more popular ''Franchise/{{Ys}}'' series, decades before the mechanic eventually appeared in FirstPersonShooter games with ''Franchise/{{Halo}}''.
* WideOpenSandbox: This was the UrExample of a fully-scaled open world. Unlike earlier role-playing games that used TheOverworld concept, the open world of ''Hydlide'' was entirely to scale, fully traversable on foot. This would later become a hallmark of ''Franchise/TheLegendOfZelda''.
* WizardNeedsFoodBadly: You must eat, and eat regularly, to survive in ''Hydlide II'' and ''Super.'' ''Hydlide II'' was, in fact, one of the first games to feature this mechanic, after ''Panorama Toh.''