Universe of Kingdom Hearts

In the Universe of Kingdom Hearts, also called the World, there are many worlds that fall into certain realms. All of these realms are on their own plane of existence.

History
According to legends, long ago, there was one single world that was constantly bathed in the warmth of the Light of Kingdom Hearts.

In the "age of fairy tales", the World was whole and full of light, which was believed to come from Kingdom Hearts, which was protected by its counterpart, the χ-blade. Over time, people came to desire the power of Kingdom Hearts, introducing darkness into the World. The event became known as the Keyblade War.

In order to take control of Kingdom Hearts, many people forged Keyblades in the image of the χ-blade, and they clashed together in a far-reaching conflict that embroiled the entire World. In the end, darkness covered the World, the χ-blade was shattered into twenty pieces, seven of light and thirteen of darkness, and the "true" Kingdom Hearts disappeared into the darkness.

However, the World was restored by the light within the hearts of children, but as many individual worlds separated from each other. The remnants of the battlefield on which the Keyblade War took place became the Keyblade Graveyard, a scarred wasteland filled with the Keyblades of fallen warriors. The remaining Keyblade wielders resolved to protect the World from further destruction, becoming guardians of the World order.

Prior to the release of the Heartless, the worlds were surrounded by barriers to prevent outside interference, making it impossible for different worlds to have contact. However, the arrival of the Heartless caused the barriers between the worlds to crumble and disappear, and some worlds were consumed by the eldritch horde. Gummi Blocks are pieces of these broken barriers.

Those who travel between worlds are advised to avoid meddling in the affairs of other worlds and informing their inhabitants of the existence of other worlds. In order to maintain a balance of separation, several characters, notably Sora, Donald, and Goofy, magically alter their physical appearances in certain worlds to avoid standing out. For example, they take the forms of sea creatures in Atlantica, monsters in Halloween Town, jungle animals in Pride Lands, and computer A.I.s in Space Paranoids and The Grid.

Sea of the Skies
The vast space between the worlds is known as Sea of the Skies (異空の海 Isora no Umi)   or Star Ocean (星の大海 Hoshi no Taikai). Ventus, Aqua, and Terra travel this space using their Keyblade Glider while Sora, Donald, Goofy and Mickey use a Gummi Ship.

Travel


Travel between the worlds is normally impossible. The worlds are all protected by dimensional barriers that prevent outsiders from entering for the most part. However, these barriers can be broken, resulting in a meteor shower in that world.

In Kingdom Hearts and Kingdom Hearts II, Sora, Donald, and Goofy use the Gummi Ship to travel between worlds on the World Map, an event that serves as a mini-game between areas. Some worlds require certain special Gummi Blocks to access; for example, a special Navigation Gummi must be installed by Cid to unlock a second set of worlds in Kingdom Hearts. Once they reach them, the party can enter and then depart each world through its Save Points. In Kingdom Hearts: Chain of Memories, there are no Gummi Ships; the worlds Sora visits are recreations from his memories from the first game brought to life on each floor of Castle Oblivion.

Four worlds can only be accessed by entering through other worlds and do not directly require use of a Gummi Ship:


 * 100 Acre Wood via Pooh's book in Traverse Town and Hollow Bastion/Radiant Garden.
 * Timeless River via the Hall of the Cornerstone at Disney Castle.


 * Space Paranoids via Ansem's computer in Hollow Bastion/Radiant Garden.


 * Keyblade Graveyard via an unknown portal at the Hall of the Cornerstone.

Methods of travel
Currently, there are five known ways to travel between the worlds:
 * Gummi: Pieces of Gummi known as "Star Shards", or the Gummi Ships built from them are able to travel the Sea of the Skies. Using Gummi Ships is much easier, as single Star Shards will cause random jumps if their handler isn't skilled in their use.


 * Lanes between (異空の回廊 Isora no Kairou, lit. "Corridors of the Skies"): The Lanes Between are a series of "roads" between the worlds in Kingdom Hearts Birth by Sleep that were unlocked by Master Eraqus. Ventus, Aqua, and Terra frequently use these paths to navigate the worlds. The presence of Darkness is very strong within them, forcing travelers to wear their Keyblade Armor as a safety precaution. To enter the Lanes, the Keyblade wielder raises his or her Keyblade to the sky, and creates a portal leading into the Lanes, appearing somewhat similar to the Dark Corridors. Upon opening the way, they usually call their Keyblade Glider and use it to enter. The Lanes resemble the Corridors of Darkness, but with a color scheme closely resembling the Aurora Borealis.


 * Gates (ゲート Gēto): After the events of Kingdom Hearts the worlds have prepared new pathways which can be accessed though the Gates.


 * Corridors of Darkness (闇の回廊 Yami no Kairou): By tunneling directly through the darkness, a traveler can move between worlds almost instantaneously. However, their direct contact with the darkness between worlds puts them at a great risk of being corrupted or engulfed by the darkness.
 * Teleportation: Certain sorcerers, like Merlin and Maleficent, are able to instantaneously transport themselves and others directly from world to world, apparently without passing through the lanes at all.
 * Time travel: Certain sorcerers, like Merlin and Yen Sid, are able to open passages to past versions of a world, or even the Sleeping Worlds, allowing travelers to move not only through space but also time.

Certain characters, such as Ansem, Seeker of Darkness and Young Xehanort, are capable of traversing through time, although the exact means of travel are still unknown. However, as stated by Xehanort, there are many limitations on time travel in this way. First, the person must "dispose of their body". Second, the person traveling must have existed in some form in the time period they wish to go to. Third, the person can only "move in one direction with the flow of time", i.e. continually moving forward into the future or backward into the past. In addition, the individual is not allowed to alter the events of that point in time. Lastly, the traveler and all those displaced from their original time will eventually return to their respective periods, with all memories of their time travel erased.

Vehicles
Two known vehicles are used as modes of transportation, whether they are powered by the aforementioned methods of travel or use an independent source:
 * GummiShip.pngGummi Ship: The main method of transportation between worlds, Gummi ships were created by King Mickey and are made entirely of Gummi Blocks. Gummi Ship travel is a slower, but a more reliable (and safer) alternative to warping by using a Corridor of Darkness, which drains one's life force. Its usefulness is not limited to travel; it can be equipped with weaponry of its own, depending on each ship's design.
 * Keyblade Glider (キーブレードライダー Kīburēdo Raidā, lit. "Keyblade Rider"): An ability only accessible to Keyblade wielders, in which the Keyblade can transform into vehicles by throwing the Keyblade into the sky, where it transforms into its vehicle form. The vehicle can be used to fly, even to other worlds, as well as attack. So far, this has only been demonstrated by Terra, Aqua, and Ventus, but it is unknown if other Keyblade wielders have this ability.

Realm of Light
The Realm of Light (光の世界 Hikari no Sekai) is the portion of the universe with an affinity for light, and is positioned opposite the Realm of Darkness. Like the Realm of Darkness, the Realm of Light has a Keyblade, the Kingdom Key, which chose Sora as its wielder. The Realm of Light is the primary setting for the series, although the protagonists sometimes travel to the Realm of Darkness, the Realm Between that connects them, or the Sleeping Worlds that lie parallel to them all.

Door to Light


The door leading to the Realm of Light is called the Door to Light (光の扉 Hikari no Tobira). It was the door Sora and Riku went through while they were stuck in the Realm of Darkness. It is not certain what caused the door to appear, though one reason could be, as Riku pointed out at the end of the game, the light within Sora's heart, which was brought out by Kairi's Letter.

Realm of Darkness


The Realm of Darkness (闇の世界 Yami no Sekai) is a realm made up of Darkness in people in every world. As with the Realm of Light, this realm has a Keyblade, Kingdom Key D, which chose King Mickey as its wielder. Kingdom Hearts is found here. This is where the most powerful Heartless can be found, as this is also the home of all the Heartless. Sora fought Ansem, Seeker of Darkness here in Kingdom Hearts. Aqua also ended up trapped here by the end of Kingdom Hearts Birth by Sleep due to saving the possessed Terra from being swallowed, effectively taking his place. Ansem the Wise ends up trapped here a second time, but lacks the way to escape like before.

Door to Darkness
The Door to Darkness (闇の扉 Yami no Tobira) is the dark counterpart of the Door to Light. It was shown to lie within the End of the World in Kingdom Hearts. Beyond the door is the Realm of Darkness where Kingdom Hearts, the heart of all worlds, resides.

Realm Between
The Realm Between (狭間の世界) is the third realm in the Kingdom Hearts series, and lies on the boundary between the Realms of Light and Darkness. Few worlds exist within it, and most have some special nature or purpose.

As of now, Traverse Town, Land of Departure /Castle Oblivion, Twilight Town, Mysterious Tower, and The World That Never Was are the only worlds confirmed to exist within the Realm Between. Each world ties closer to the Realm of Light or the Realm of Darkness, with the exception of Twilight Town, which exists exactly in the middle.

Sleeping Worlds
The Sleeping Worlds (夢見る世界) are a place where parts of worlds go after their hearts have been taken over by darkness. After Sora sealed the Door to Darkness with help of Mickey, many worlds were restored from their demise, but some of them were submerged into deep sleep that prevented them from waking fully for a year. Sora and Riku are sent into Realm of Sleep in order to release those worlds and complete their Mark of Mastery exam.

While Heartless and Nobodies reside in Realms of Light and Darkness, in the Sleeping Worlds Dream Eaters take their place.

Sora and Riku travel through worlds such as Destiny Islands, La Cité des Cloches, The Grid and Prankster's Paradise in order to release them from their sleep. They also travel to worlds whose dreams are of the past such as Country of the Musketeers and Symphony of Sorcery. Traverse Town also appears within this Realm, brought into being for Joshua to be able to save Neku and his friends from the demise of their own world.

Worlds


A World (世界 Sekai) is a location that appears in the Kingdom Hearts series. Serving as the "levels" for the games, Sora and other characters are charged with visiting and protecting them through the course of the series. By defending the worlds from the Heartless, Nobodies, or other enemies, Sora keeps the Darkness from spreading and the worlds from being manipulated or destroyed. At the end of every world Sora, Donald, and Goofy have to fight a boss of that world (which is either a giant Heartless or a Disney villain) which opens the Keyhole area when defeated. At the end Sora locks the Keyhole and earns a Gummi that will let him go to the next world.

Each world that appears in the Kingdom Hearts series has its own distinct look, and for the most part hold true to the movies and cartoons they are based on. Often the plot of the game in that world will be based on its original source. Almost all worlds can be visited in the course of the game and are part of the playthrough; there are exceptions, though, since some places can be seen in cinematics but not actually accessed by Sora's party. All worlds are separate from one another, and with a few exceptions, most people are unaware of the existence of other worlds.

World characteristics
There are over thirty worlds that have appeared in the Kingdom Hearts series so far. Most of them are based on Disney's animated features and contain locations and characters from or inspired by the films. As a result, worlds are greatly varied in appearance, style, and nature, as their sources range from the oldest cartoons created by Disney to more current movies in the Disney canon.

The oldest source is the 1928 cartoon Steamboat Willie, used as a basis for Timeless River, while the most recent inspiration for a world from Disney's animated features is 2002's Lilo & Stitch, the source for Deep Space. In Kingdom Hearts II, two live-action films, Pirates of the Caribbean: The Curse of the Black Pearl and Tron served as the foundation for the worlds Port Royal and Space Paranoids, respectively. In Kingdom Hearts 3D: Dream Drop Distance one direct-to-video movie, Mickey, Donald and Goofy: The Three Musketeers, which served as the source for Country of the Musketeers, makes it the first world in the series to originate from a direct-to-video film, instead of a film from the animated features canon.

In addition to the Disney-based worlds, twelve worlds are exclusives that were created by game developers Square Enix just for the Kingdom Hearts series. They are not part of the Disney film canon, nor Square Enix's games canon, but do tend to be populated with Square Enix characters, especially from the Final Fantasy series, as well as the occasional Disney character or original characters created just for Kingdom Hearts.

Some worlds have names that don't seem to accurately reflect what is found there. A famous example is Neverland in Kingdom Hearts; Sora and company get to go through Captain Hook's ship and fly around the Clock Tower, but never actually reach the island Neverland where Peter Pan and Tinker Bell live. To further confuse things, some worlds in Kingdom Hearts II contain what could almost be considered sub-levels or second worlds within them, such as the Underworld at Olympus Coliseum or Christmas Town in Halloween Town.

Keyholes
A Keyhole is a gateway in each world that leads to the heart of that world. The Heartless invade worlds and search for their Keyholes. Upon discovering the Keyhole, the Heartless will enter it and eventually devour the world's heart. After a world's heart is consumed, the world crumbles, and fades from existence. It is said that, if the Keyblade locks a world's Keyhole, it can never be opened again. Thus, Sora, along with Donald and Goofy, travel from world to world to seal the Keyholes using the Keyblade.

Gates (ゲート Gēto?) are special pathways into worlds in Kingdom Hearts II which are opened when a specific item or object, different for each world, is surrounded in light and is accompanied by a gust of wind. The item in question reveals the Keyhole to a route to another world, allowing Sora to open it.