Kingdom Hearts has been one of Square Enix’s most popular franchises ever since it began over 20 years ago, a legacy that’s likely to be continued when Kingdom Hearts 4 eventually releases. Well known for featuring a convoluted but wholesome plot across the Dark Seeker Saga, which ended with the third entry, the Kingdom Hearts games at their best feature some of the most creative storytelling that the medium has to offer.

The original was released back in 2002, but the prequel side of the Kingdom Hearts timeline only came to be explored years later. It was after Kingdom Hearts 2 and multiple spin-offs like Chain of Memories that the time before Sora was properly depicted, but it has become one of the memorable sides of the series for many fans. As the next mainline title is set to delve into the enigmatic new Lost Master Arc, the past of Kingdom Hearts could become more relevant than ever.

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Kingdom Hearts Union X Dark Road

Originally released as Kingdom Hearts X, this prequel is set centuries before the events of Sora's first adventure. It takes place in a time when a group known as the Foretellers rallied unions of keyblade wielders to collect light; X would lead into the historical Keyblade War referenced in the main series. Union X would go on to serve as an update that continued the story in a data simulation for most of its run. Seeing the end of the conflict of its characters in Daybreak Town, this mobile game’s ending directly set up the location of Scala ad Caelum in a connection to Kingdom Hearts 3.

Kingdom Hearts Dark Road was technically a continuation of Union X, but it was instead focused on the origins of Dark Seeker Saga antagonist Xehanort. Set during a youthful era that sees Xehanort being heroic as the student of a keyblade master alongside Eraqus, Dark Road sets up the events of all the original titles fans are familiar with. Featuring a dramatic story centered around the betrayal of one of Xehanort’s close friends, this game skips forward in time at the very end following these events. After 60 years of studying darkness, Xehanort becomes the villain seen in his first appearance.

Kingdom Hearts Birth by Sleep

Birth by Sleep is set a decade prior to the first Kingdom Hearts. Focused on the trio of Terra, Ventus, and Aqua, this game sees them all ultimately encounter tragedy in ways that lead directly into the mainline games. Fantastical keyblade transformations and three separate narratives made this game a turning point for the franchise as a whole. Sora, Riku, and Kairi even make appearances as small children in passing of the torch moments that made it clear the world of Kingdom Hearts existed long before them. The first title to prominently feature Master Xehanort, Birth by Sleep has an even more connected role in the Kingdom Hearts timeline after years of further development.

Included in the Kingdom Hearts HD 2.8 Final Chapter Prologue collection, the game Kingdom Hearts: 0.2 Birth by Sleep -A fragmentary passage- serves to bring the stories of several key titles together. With its connection to Dream Drop Distance in Mickey, 0.2 ties Birth by Sleep’s ending into the lead-up to Kingdom Hearts 3. Seeing Aqua journey through the Realm of Darkness during the 10 years in which she was trapped there, she witnesses the events of the series from an outside perspective. Reviewing nearly the entire timeline through Aqua’s eyes, 0.2 still seems to begin years before the first Kingdom Hearts. As Kingdom Hearts 4 is set to push the series into the fictional reality of Quadratum, perhaps another game in this style could end up similarly helping the transition one day.

Kingdom Hearts 4 is in development.

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