Hyrule is an ancient land of myth and legend. The timeline of The Legend of Zelda spans thousands of years, and yet, only a handful of years have ever been seen in game. Link, Zelda, and Ganon are the focal points, and as such we've only heard tales of the eras in-between their battles.
Many of these eras are interesting enough to warrant a game of their own. They could follow Hyrule Warriors' example and explore other genres as well. The Legend of Zelda is a well of possibility and these periods deserve more than a brief mention in the Hyrule Historia.
10 The Era Of Hylia: The First Incarnation Of Hatred
A prequel to Skyward Sword is not the first thing many would pitch in an elevator, but the origins of Hyrule are still vastly unexplored. A game centered around the founding of all civilization would be astounding. Hylia also had her chosen hero, so it could be a more traditional action-adventure Zelda game.
The meat of the game could follow after Breath of the Wild, giving Skyward Sword the open world it always wanted to have. The game could focus on Hylia and the chosen hero meeting all the races of Hyrule for the first time, and establishing millennia old relationships. If nothing else, this game could be a fan-service potluck with allusions towards later parts of the timeline.
9 The First Great Calamity: A Lost Legend
Breath of the Wild practically screams "PREQUEL MATERIAL!" at you. 10,000 years prior to the start of the game something happened. A princess, a hero with a sword, and some robots rose up to defeat Ganon when he first abandoned his physical form. That's the plot of almost any Zelda game, but there's one major twist to the formula: the hero had red hair.
This era featured a completely unknown hero. Besides being the starting point for countless fanfictions, that's an interesting premise to start a game on. They supposedly wielded the Master Sword, but that's about all we know. If this isn't Link, this would be a fascinating character to meet.
8 Hyrulean Civil War: Unification
The origins of the Hero of TIme are tragic despite his lack of knowing so. The events preceding Ocarina of Time paint anything but a pleasant picture, as Link is raised as an orphan of war. A war Ganondorf was instrumental in leading against the forces of Hyrule. Despite being instrumental in the shaping of key characters, much is unknown about this war.
Because of the heavy political atmosphere of the Hyrulean Civil War, a game in this era could be strikingly similar to Mass Effect. You could explore the realms of the Gorons, Deku, and Zora to build your army to repel Ganondorf's. The game would also likely take on a darker tone.
7 The Imprisoning War: The Hero's Defeat
The timeline split is peculiar for having one timeline that runs almost independently of the other two. While the Adult and Child Timelines are the result of time travel, the Downfall Timeline happens if Link dies while the Seven Sages are free. The result is the Imprisoning War where the sages mustered all remaining forces in Hyrule for one last push against Ganondorf.
Prior to Breath of the Wild, this was canonically the only time the hero failed to stop the incarnation of hatred. The tone for a game in this era would be explicitly somber, set during Hyrule's lowest hour, and would play out as a full-scale war. As a result, the Hyrule Warriors series could be a great fit for this era.
6 The Great Flood: An Era Without A Hero
Ocarina of Time is the focal point for much of the series, and it's no surprise the eras surrounding it are so interesting. The Great Flood is the result of Link being sent back in time at the end of Ocarina, so no hero is left to defend the future. Flooding Hyrule is the only way to keep the Triforce away from Ganondorf when he inevitably returns.
Would it be bizarre to propose a visual novel spin-off? This could turn into another army building simulator, but given the dramatic irony dictating everyone's death, it could be compelling, and tragic, to walk through the lives of everyone present during this era.
5 End Of The Shadow Era: The Four Sword
Four Swords Adventure, one of three multiplayer Zelda games, isn't the first thing people think of when they think "lore bomb" for the series, and yet, it is. Traditionally, the spirit of Hylia and the Hero have been reborn multiple times, but Demise has only been reincarnated twice. Once in Ocarina, then again in Four Swords Adventure. Once this Ganondorf is sealed however, he's never heard from again.
The Shadow Era is wholly unexplored. It is the era after Four Swords Adventure, and nothing more. Instead of the Master Sword, the identity splitting Four Sword is the focus, the fan favorite Wind Mage Vaati is a recurring antagonist, and there is a second Ganondorf. How has there not been a game expanding on this era already?
4 The Interloper War: Beautiful Twilight
The Interloper War is integral to the backstory of Twilight Princess. Despite that, the game doesn't dwell on the topic for very long. It's just enough to explain that a group of traitors abused dark magic and were sentenced to the Twilight Realm. In truth, not much more needs to be said to understand the event, but appreciating it could go a long way.
Zelda's magic system is a bit loosey-goosey. Magic just kind of — is. Still, the idea of dark magic, its taboos, and its ramifications are uncharacteristically grim for Zelda. To match the motif of actions having consequences with the gameplay, this game could be molded after Fire Emblem. Characters lives hold weight, and losing them is permanent.
3 The Great Voyage: Building A New Hyrule
Sometime between Phantom Hourglass and Spirit Tracks, Link and Zelda founded a new Hyrule after their great voyage. This is hand-waved at the start of Spirit Tracks, but that's kind of a big deal, so can we dwell on it? There's a whole new Hyrule, with a brand-new history and culture to explore, and you could have a hand in shaping it!
What better way to explore this era is there than with a city builder? You could plan the infrastructure of Hyrule while also making decisions on how new temples are built. You wouldn't just be building a city — you would be building a kingdom. Building a city for the Gorons could be totally different from building for a Hylian.
2 Whatever Led To The Timeline Merger: ASTERISK!
While Zelda is famous for its split timeline, Breath of the Wild all but confirms that the timelines have merged. Pieces of all three timelines can be found in this one world, and how this happened should be an important time to explore. As a full-blown RPG, this would allow you to interact with fan-favorite characters and areas from all three timelines.
Such a game would be great, and they almost did that. Hyrule Warriors is basically this, but it's not brave enough to be canon. It also doesn't allow you to interact with the world much. It's all combat, but the merging of three timelines would have social intrigue as well.
1 The Hero Of Time's Final Years: A Hero Beyond Legend
Fate is cruel, and the Hero of Time is no stranger to its twists. In one timeline, he dies. In another, he's sent away from the world he saved, and in another, he is sent back in time where his friends don't recognize him. Then, the next time we ever learn of him is in Twilight Princess where he died in the Lost Woods, a nameless soldier.
It's heartbreaking how the Hero of Time's story ends. In Twilight Princess, it's clear he's a gained lifetime of combat experience. He's likely the greatest swordsman to ever live in his time, and he's nameless. His story can't end with a whisper.