Kingdom Hearts Final Mix was a previously Japan-exclusive reissue of Kingdom Hearts, released on December 26, 2002. Final Mix was released in other territories with Kingdom Hearts HD 1.5 ReMIX in 2013. The game uses English voice acting with Japanese subtitles among additional in-game features.
Depending on what store the game was pre-ordered, customers could get a CD containing tracks from the game or a playing card set adorned with Kingdom Hearts characters and symbols. At some stores in Japan they were giving away a dual Keyblade embroidered necklace with a pre order.
Kingdom Hearts Final Mix Platinum Limited
Kingdom Hearts Final Mix Platinum Limited came in a box containing the game case, a sheet of eight Kingdom Hearts stickers; a postcard calendar featuring Tetsuya Nomura artwork and—contained in a CD case—a block figure of Sora, part of Square's Minimum Collection; and three can badges. The set costs 8,800 yen.
Kingdom Hearts 1.5 HD ReMIX
Kingdom Hearts Final Mix is included in the Japanese, European, North American, and PAL region releases of Kingdom Hearts 1.5 HD ReMIX. The Japanese version has English-voiced cutscenes changed to Japanese, along with unvoiced cutscenes, while the other distributions have English voices and texts, as well as the unvoiced cutscenes added to this title.
Kingdom Hearts Final Mix features changes from the original version, including bosses present in the English version, but not in the original Japanese version. Other changes include the recoloring of some Heartless and introducing new ones, new weapons, new enemies, new abilities, new cutscenes, Gummi Ship missions, new Ansem's Report, and a new secret movie.
The start screen was replaced with another drawing of Sora, hooded and holding a flag. On the start screen, a trailer for Final Fantasy X-2 is accessible, labeled as a "Special Movie" as a third option after "New Game" and "Load Game". The game has three difficulty levels, the first being Final Mix: Beginner, which gives the player a Ribbon, an EXP Necklace, 8 Power Ups, 8 Guard Ups and 4 AP Ups at the start, but neither of the secret movies can be seen. The Drill Gummi's Attack Power is 9,999, instead of 35. The second difficulty is simply "Final Mix", analogous to Standard from the previous game, but not the exact same. The Gummi Ship takes double the damage from the original version and damage inflicted by the player is cut by a third. The last option is Final Mix: Proud, a greater challenge than Expert from the original game. The Gummi Ship's attack is reduced further to a half, and damage is four times. Upon finishing the game, a "Battle Report" is shown, providing the player with various statistics of the playthrough.
Another new feature includes an Event Skip option, allowing the player to skip cutscenes already seen. Sora is modified to become transparent when camera situations force.
A bug involving a red Trinity located in Oogie's Manor was fixed. In the original game, if the player did not use the Trinity prior to defeating Oogie Boogie, the trinity would disappear. The trinity was moved to an area below an arch near the manor; however, in Kingdom Hearts 1.5 Final Mix the trinity will remain on the arch despite being used.
The new bosses included "the Unknown", who was introduced with no context and later revealed to be Xemnas, leader of Organization XIII in Kingdom Hearts II and Kingdom Hearts 358/2 Days . Also added were "palette swap" bosses for the Olympus Coliseum: Destroyed Behemoth, Arch Behemoth, Red Armor, and Sneak Army. New to the Japanese were bosses included in the English version: Sephiroth, Ice Titan, and Kurt Zisa. Most Heartless were recolored and several new ones were added, such as the Chimaera, Gigas Shadow, and Pot Scorpion
Two new weapons were added for each main character. These serve as 'secondary ultimates', with one having more power than the regular ultimate weapon (Ultima Weapon, Save the King, and Save the Queen) usually with an MP reduction, while the other has more Magic potential with low physical capabilities. Sora gains two Keyblades: One Winged Angel and Diamond Dust, Donald gains two staffs: Meteor Strike and Fantasista, and Goofy gains two shields: Mighty Shield and Seven Elements.
New abilities and accessories were added as well.
Several new cutscenes were added. The first, shown after Sora fights Leon in Traverse Town, has Riku lost in Hollow Bastion, calling out for his friends and Maleficent looking on. Another, played after Sora speaks to Kairi in the underground waterway in Traverse Town, showed Riku lost in the Realm of Darkness after Ansem, Seeker of Darkness took his body. There, he is assisted by King Mickey who reveals that he has the realm's Keyblade. Neither of these cutscenes used any new audio and instead the subtitles were seen on a black screen.
An optional cutscene was a confrontation between Cloud and Sephiroth, seen after the player defeats Sephiroth. Cutscenes were provided for the Unknown, using spliced voice acting for Sora and Goofy, but shaking text on a black screen for the Unknown.
A minor cutscene was also added near the start of the game on the second day on Destiny Islands, where it is revealed that the lucky charm Kairi makes out of Thalassa Shells is the Oathkeeper charm she later gives to Sora.