Kingdom Hearts Union χ

Kingdom Hearts Union χ[Cross], previously named Kingdom Hearts Unchained χ (キングダムハーツ アンチェインドキー), is a Kingdom Hearts game exclusive to the iOS and Android smartphone platforms. It features plot and gameplay elements from the Japan-exclusive web browser game Kingdom Hearts χ, and it is free to play but contains in-app purchases. It is the first Kingdom Hearts game to be released on smartphone platforms.

Kingdom Hearts Unchained χ was first announced on May 12, 2015. During Square Enix's E3 Conference on June 16, 2015, a trailer for the game was released showcasing gameplay. Kingdom Hearts Unchained χ was released in Japan on September 3, 2015 and in North America on April 7, 2016.

In April 2017, the game was rebranded with the Kingdom Hearts Union χ[Cross] content update, featuring multiplayer and a theater mode.

Development
While there were rumors of a localization for the web-browser based Kingdom Hearts χ, the smartphone game wasn't publicly referenced until April 14, 2015, in an interview with Tetsuya Nomura. The game was officially revealed on May 12, 2015, with the official title revealed in Famitsu magazine the following day.

On December 7, 2015, Version 1.1.0 was released. It raised the maximum level of Keyblades, added Adamantite Ore and matching quests, added Upright and Reversed Keyblade slot bonuses, and Special Attack Bonus.

On March 31, 2016, Version 1.2.0 was released. It raised the maximum Player level to 300.

On April 7, 2016, Kingdom Hearts Unchained χ was released in North America, starting at version number 1.0.0.

On August 4, 2016, Version 1.3.1 was released for the Japanese version. For the English version, it was called Version 1.1.2, and released on September 1, 2016. It added a Perks system for Avatar Parts, a daily Lux Boost function, and the ability to set up to three decks per Keyblade.

On November 2, 2016, Version 1.4.0 was released for the Japanese version. For the English version, it was called Version 1.2.1, and released on November 10, 2016. It added the Nova system.

On March 23, 2017, Version 2.0.0 was released for the Japanese version. For the English version, the update was released on April 6, 2017. It renamed the game to Kingdom Hearts Union χ, and added Union Cross multiplayer mode, Theater Mode, Medal Traits, Tutorial Quests, raised the cap for buffs and debuffs to 7, and the cost cap for Medals to 20.

On July 13, 2017, Version 2.2.0 was released for the Japanese version. For the English version, the update was released on July 20, 2017. It added completion percentage and icons to the Quest screen, MVP rewards for Union Cross, and a Perk filter feature for Avatar Parts.

On September 21, 2017, Version 2.3.1 was released for the Japanese version. For the English version, the update was released on September 28, 2017. It added the Pet System, increased the amount of jewels obtained as login bonus, made adjustments to several Story Quests, and changed the special attacks of all 4★ and lower Medals to match the 5★ version.

On November 2, 2017, Version 2.4.0 was released for the Japanese version. For the English version, the update was released on November 8, 2017. It added Booster items, the Mission feature, and added Auto battle to quests.

On January 18, 2018, Version 2.5.0 was released for the Japanese version. For the English version, the update was released on February 1, 2018. It added a low resolution option, and the option to display draw odds for Medal deals.

On March 23, 2018, Version 2.6.0 was released for the Japanese version. For the English version, the update was released on March 25, 2018. It added PvP Mode, 7★ Medals, Keyblade subslots, an optimize button for Keyblades, allowed players to skip certain Story Quests, and reduced the required materials for upgrading Keyblades, while removing some materials and matching special quests.

On July 12, 2018, Version 2.7.0 was released for the Japanese version. For the English version, the update was released on July 19, 2018. It added the option to flee from Raid battles, made damage indicators easier to read, and made some adjustments to the UI in PvP.

For a full list of updates and changes, visit the page on the Kingdom Hearts Unchained χ Wiki.

Story
Prior to the Keyblade War, Strelitzia, a member of the Dandelions selected to be one of the new Union leaders once the war ends, attempts to convince Player to join the Dandelions, but she was eliminated by an unknown individual, who then steals her rulebook and takes her place as Union leader.

After being saved by Ephemer and Skuld following the conclusion of the Keyblade War, Player is brought to another realm, where the Dandelions have assembled, as per Ava's instructions. Upon entering this new realm, everyone loses all their memories of their previous world, with the exception of the five wielders chosen to become the new Union leaders.

Following Ava's orders, Ephemer, Skuld, Ventus, Brain, and Lauriam gather at the Keyblade Graveyard to meet with their fellow Union leaders, with Lauriam being the last to arrive. Together, the five enter the Foretellers' Chamber in Daybreak Town, where Brain looks through a copy of the Book of Prophecies that he finds. Ultimately, they decide to keep the Unions united under a Union χ to prevent future conflicts between Keyblade wielders. Brain decides that in order to celebrate, they should make creating new Spirits their first task, sending Ephemer, Skuld, and Ventus to collect the supplies while he and Lauriam prepare to synthesize the materials.

Meanwhile, Player resumes their missions, initially reliving through the events leading up to the Keyblade War, and later making use of the newly created Union χ, joining a party of fellow Dandelions and traveling to new worlds. Soon, Player begins having nightmares of the Keyblade War. Chirithy, concerned of the frequency of Player's nightmares, reports this to Ephemer and Skuld, who encourages Chirithy to protect Player from the truth. Afterwards, Ephemer and Skuld begin to investigate a new impending darkness in the world.

Changes from Kingdom Hearts χ

 * have been replaced with s.
 * Players are able to switch genders and Unions at any time.
 * Overworlds have been replaced with the Quest system.
 * Action Points have been overhauled; they now function as a stamina system that enable the player to enter Quests and start Raids.
 * BP has been removed.
 * Lux and EXP have been consolidated.
 * New Heartless have been added.
 * New Keyblades have been added:
 * Stroke of Midnight
 * Fairy Stars
 * Sleeping Lion
 * Counterpoint
 * Fenrir
 * Darkgnaw
 * Missing Ache
 * Diamond Dust
 * New Worlds have been added:
 * Castle of Dreams
 * Enchanted Dominion