Kingdom Hearts Unchained χ

Kingdom Hearts Unchained χ, later renamed as Kingdom Hearts Union χ[Cross], 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 and renamed with the Kingdom Hearts Union χ[Cross] content update, featuring multiplayer and a theater mode.

Changes from Kingdom Hearts χ
Castle of Dreams
 * 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:
 * Munny Egg
 * Gold Tricholoma
 * Burst Balloon
 * Green Requiem
 * Emerald Sonata
 * Trouble Candle
 * Huge Shenaneggan
 * Poison Pot
 * Rush Rat
 * Rush Rat Tri
 * Bane Spider
 * Wicked Spider
 * Malice Spider
 * Enraged Arachnid
 * Jewel Sorceress
 * Jewel Princess
 * Adventurer
 * New Keyblades have been added:
 * Sleeping Lion
 * Counterpoint
 * Stroke of Midnight
 * Fenrir
 * Darkgnaw
 * Missing Ache
 * New Worlds have been added:
 * Cinderella
 * Prince Charming
 * Grand Duke
 * Jaq
 * Fairy Godmother
 * Lady Tremaine
 * Anastasia
 * Drizella
 * Lucifer

Union χ Update

 * The game was rebranded and renamed from Unchained χ to Union χ[cross] - with the rebranding came a new logo and artwork.
 * The story immediately picks up following the events of the final missions in Unchained χ. Whereas in that game players were able to craft a custom avatar who would go on to play a role in the Keyblade War, in Union χ the player character is a member of the Dandelions.
 * The game retains the gameplay found in Unchained χ, and all in-game data will be carried over.
 * Multiplayer is introduced. Players will be able to team up with up to five members of their Party and tackle special Quests together.
 * Theater Mode has been added, allowing players to view all story cutscenes they've experienced at any time.