The CD-i Zelda Games
Between 1993 and 1996, three Zelda games came out that Nintendo didn't make, on a console Nintendo didn't make. They're the Philips CD-i Zelda games, and they're some of the most famous oddities in video game history.
In the early 1990s, Nintendo worked with Philips on a CD-ROM add-on for the Super Nintendo. The add-on never came out, but as part of the deal Philips got the right to use some of Nintendo's characters on its own CD-i multimedia player. Philips used that right to make three Zelda games, plus a Mario game. Nintendo wasn't involved in making them, and they don't count as part of the official Zelda story. They are still the only licensed Zelda games ever released on a non-Nintendo system.
Link: The Faces of Evil
Philips CD-i · 1993 · Animation Magic · Play as Link
Hyrule is at peace, and Link is bored. That changes when the wizard Gwonam flies in on his magic carpet with bad news: Ganon has taken over the island of Koridai and is turning its people into monsters. An old prophecy says only Link can stop him, so the two fly off to Koridai.
The island is ruled from its Faces of Evil, huge mountains and fortresses carved in the likeness of Ganon's minions. Link has to beat each of their masters (Goronu, Harlequin, Militron, Glutko and Lupay) before facing Ganon in his own lair. Along the way he learns that Ganon has also captured Princess Zelda and put her under a sleeping spell. In the end, Link defeats Ganon with the magical Book of Koridai, which traps the villain inside its pages, then wakes Zelda by ringing a gong.
It plays as a side-scroller, much like Zelda II: The Adventure of Link. Link picks stages from a map of the island, fights through them, and spends Rubies (the CD-i games' name for Rupees) on gear at Morshu's shop. Talking to people means touching them with the "Smart Sword", a sword that won't hurt friends, which plays an animated cutscene.
Zelda: The Wand of Gamelon
Philips CD-i · 1993 · Animation Magic · Play as Zelda
Made alongside Faces of Evil and released on the same day, The Wand of Gamelon turns the tables: it's the first game in the series where Princess Zelda is the hero. King Harkinian sails to the island of Gamelon to help its ruler, Duke Onkled, fight off Ganon, telling Zelda to send Link after him if he doesn't come back within a month. A month passes, then Link vanishes too, so Zelda sets off with her nursemaid Impa to find them both.
Zelda battles Ganon's minions across Gamelon, including Gibdo, an Iron Knuckle, the Three Witches, Wizzrobe, Hectan and Omfak, and discovers that Duke Onkled has betrayed the King. The only weapon that can stop Ganon is the Wand of Gamelon, hidden in the Shrine of Gamelon. With it, she traps Ganon in a chained book, rescues her father, and finally frees Link, who had been stuck in a magic mirror all along. Onkled's punishment? Scrubbing every floor in Hyrule.
It plays almost exactly like Faces of Evil: a side-scroller with stages picked from a map, items found or bought along the way, and fully animated cutscenes between the action.
Zelda's Adventure
Philips CD-i · 1996 · Viridis · Play as Zelda
The last of the CD-i games was made by a different studio, Viridis, and it looks and plays nothing like the other two. Hyrule's region of Tolemac has fallen into an Age of Darkness. "Gannon" (as the game spells him) has captured Link and stolen the seven Celestial Signs, hiding them in shrines guarded by his Shrine Keepers. The astronomer Gaspra calls on Princess Zelda to win back the Signs, rescue Link and bring an Age of Lightness back to the land.
This time the view is from above, like the original Legend of Zelda. Tolemac is split into screens, and there are real dungeons, the seven shrines, complete with maps and compasses, which have to be cleared in order. Zelda fights with a wand instead of a sword and collects spells for it, each costing Rupees to cast. The overworld is made from photographs of real scenery, and the cutscenes are live-action video instead of animation.
It came out in very small numbers in 1996, as the CD-i itself was being discontinued, so it's by far the rarest of the three.
Their Legacy
When they came out, the CD-i games got mixed reviews at best, and later critics have been even harsher: the controls are clumsy, the games are hard, and the stories are very loose takes on Zelda. More than a decade later, their cartoon cutscenes found a second life online. Lines from King Harkinian, Morshu the shopkeeper and Gwonam became some of the internet's most remixed video clips.
Nintendo has never re-released them and doesn't count them as part of the series' story. Even so, they're a real, licensed part of Zelda history, and The Wand of Gamelon has the honour of being the first game where you could play as Princess Zelda, long before Echoes of Wisdom.