Kingdom Hearts: Chain of Memories

Combat uses a card-based battle system executed in real time.[6][11] The player can jump and maneuver around the battle screen as they would on the field map, but all physical attacks, magic, items and summonings are activated by playing cards.[4] Cards are ranked from zero to nine, and are used for making attack combos or breaking enemy cards. With the exception of zero-ranked cards which are more expensive in terms of Card Points (CP) compared to other cards of the same type and have other ranks, more CP are required to place higher-ranked cards in the player's deck. Card Points—increased through level up—limit the number of cards the player can use in a deck. Cards with rank "zero" can break any opposing card or combo if played after the opposing card or combo, but they can be broken by any card or combo as well if it is played after the zero card is played.[12] Breaking an opposing card will cancel that attack and stun the loser of a card break for a short time. Special enemy cards may be obtained by defeating enemies and bosses, and are used to give the player a temporary ability, ranging from enhanced offensive and defensive capabilities to modifying the attributes of certain cards.

Combining cards in sets of three will create combo attacks that are usually more difficult to break because the rank of the combo will be the sum of the ranks of the three cards in the combo. Certain card combinations will create a "sleight", a special combination that will create a powerful physical attack, magical spell, or summon attack.[9] When the player runs out of cards, the deck must be reloaded. Additionally, using a card combination will cause the first card in the combo to become unusable until the end of combat.[8]

Sora's and Riku's stories differ gameplay-wise in several ways. In Sora's story, Sora obtains cards by defeating enemies or through Moogle Shops.[9] In some cases, Sora must earn the specific card first through a plot event before it becomes available. Sora can create and store three different decks in the pause menu. Unlike Sora, Riku has a closed deck that cannot be customized. The cards in his deck change depending on the world in which he is traveling. Riku is limited to mainly physical attacks, enemy cards and Mickey Mouse ally cards. He can activate "dark mode" and unlock his sleight attacks if he accumulates enough "dark points". Dark points are earned by breaking enemy cards and combos, and the difference between Riku's card or combo and the enemy's card or combo is how many dark points he will accumulate for that card break.[10]

Kingdom Hearts: Chain of Memories is set immediately after the events of the first game.[13][14] It is set in Castle Oblivion, a mysterious castle kept by Lord Marluxia.[15] Sora and his teammates are told that the castle causes visitors to lose their memories upon entering.[16] The lobby and areas between floors are white with flower-themed decorations, but each floor can be transformed into a different world from the first Kingdom Hearts game using "world cards" created from Sora's memories.[10][17] Like before, many of the worlds of Disney and Square Enix reappear.

Unlike the previous game, the worlds are created from Sora's memories. As such, many of the events experienced in Kingdom Hearts are relived in this game, Sora encounters memory-based versions of Disney characters that he has met before (except Deep Jungle in Tarzan). The individual plotlines differ from those in the original game and revolve around the theme of memory. Just as Kingdom Hearts had several worlds created specifically for that game, Chain of Memories introduces Twilight Town as a world created from memories on "the other side of [Sora's] heart",[18] in addition to the original worlds of Kingdom Hearts.

Sora returns as the game's protagonist.[1] Donald Duck and Goofy are less involved in the gameplay and story. Like the first game, Chain of Memories features numerous characters from both the Final Fantasy series and the Disney animated features canon. Being a direct sequel, many of the characters from the first Kingdom Hearts reappear in this game. As each world and the related characters are recreated from Sora's memories, they interact with Sora as if they had never met before. The game also introduces a handful of new characters. Several are members of the enigmatic Organization. Other new characters include Naminé, a young girl capable of manipulating memories, and DiZ, a mysterious man concealed by red robes and bandages. Riku appears as a playable character in the second story mode. After being sealed in the realm of darkness, Riku heads to the basement of Castle Oblivion, aided by King Mickey Mouse and DiZ.

Six members of the Organization serve as antagonists; four appear in Sora's story mode, and the other two in Riku's. Among the four Sora encounters are Marluxia, the lord of Castle Oblivion; Larxene, Marluxia's assistant; Axel, a double agent with hidden loyalty; and Vexen, Marluxia's unwilling collaborator. Conversely, Riku battles Zexion and Lexaeus, Vexen's allies. Ansem also appears in Riku's story as an entity that attempts to control Riku. Many of the Disney villains return via memory-based recreations like the rest of the Disney characters.

Sora, Donald, Goofy, and Jiminy Cricket walk down a winding path in search of Riku and King Mickey. A man dressed in a black, hooded coat appears and directs Sora towards a massive fortress called Castle Oblivion.[10] Upon entering, the travelers realize that they have forgotten all their abilities.[16] The hooded man explains that the deeper they go into the castle, the more memories they will lose, but they will also uncover new memories in the process.[19] He creates a deck of cards made from Sora's and his friends' memories, and tells them that everything they encounter in this castle will be based on their memories.[6]

Sora ascends the castle, facing off against other hooded figures who form a group called "the Organization" along the way. As Sora loses his memories, he gradually appears to remember a girl named Naminé as an old friend of his, and learns from Organization member Larxene that she is being held prisoner in the castle.[20] He also clashes with a replica of Riku created and controlled by another Organization member, Vexen, and believed by both Sora and the replica himself to be the real Riku. Axel, an Organization double agent, releases Naminé and allows her to meet Sora in person. Sora discovers Naminé to be the one manipulating his memories, having been forced to do so by Marluxia, the lord of Castle Oblivion and the figure who lured Sora there, as part of his plan to overthrow the rest of the Organization with Larxene.[21] Sora climbs to the highest floor and defeats Marluxia, after which Naminé puts Sora and his friends into pod-like machines to help them regain the memories they have lost, even though they will forget the events that transpired in the castle.[22] Before they are put to sleep, Sora and Naminé promise to meet again as real friends once he reawakens, Sora firmly believing that his memories of her and the castle will remain in his heart despite being forgotten.[23]

In Reverse/Rebirth, which occurs congruently with the game's main story, Riku is transported from the realm of darkness to Castle Oblivion's deepest basement, and he fights figments of previous enemies to combat his inner darkness as he climbs upwards. Vexen fights Riku to obtain his data and creates his replica to counter Marluxia's plan. Ansem, still possessing Riku's body, tries to regain control of Riku, but Mickey's power keeps Ansem at bay.[24] On the way, Riku battles and defeats Lexaeus, a member of Vexen's circle, only to be dragged into the realm of darkness. However, he is saved by Mickey when Ansem nearly succeeds in taking Riku's body as his own. With Marluxia eliminated by this time, another of Vexen's allies, Zexion, attempts to dispose of Riku by drowning him in light. Riku is saved by Naminé disguised as Kairi, who helps him to control his darkness, allowing him to defeat Zexion. Riku later meets DiZ, an enigmatic individual interested in Riku who sends him to find Naminé.[25] Riku's replica, who has since learned of his altered memories, seeks to justify his existence by killing Riku, only to be destroyed by him. Riku chooses to face Ansem upon learning from Naminé that Ansem lives in his heart, and defeats him after DiZ summons him for Riku to fight. Riku then sets out on a journey to utilize both his darkness and his light with Mickey as his companion.[26]

Much of the music from the original Kingdom Hearts is present in Chain of Memories; the main vocal theme for the Japanese release is "Hikari" (光), while the English version of "Hikari", "Simple And Clean", is used in the Western releases.[38] Additional and reworked tracks were created for its PlayStation 2 rerelease, Kingdom Hearts Re:Chain of Memories. Since the music is reused from the original, a Chain of Memories soundtrack was never released. The new reworked tracks, however, are included on two CDs in the Kingdom Hearts Original Soundtrack Complete.[39]

Due to the technological limitations of the Game Boy Advance cartridge size, voice acting was kept to a minimum. Though many characters from Kingdom Hearts were voiced by the cast from before, the Japanese version used the following voice actors: Keiji Fujiwara as Axel; Tatsuya Kando as Vexen, Marluxia, and Lexaeus; and Rieko Katayama as Larxene.[40] A limited amount of voice acting was added only for the battle sequences.[41] Voice clips from the first Kingdom Hearts were inserted into Chain of Memories.[42] The English version is absent of dialogue; voices during Organization battles are replaced with simple grunts, laughter, and other battle cries.

Comparison of a scene involving Sora, Donald, Goofy and Aerith on the GBA (top) and the PS2 (bottom).

Kingdom Hearts: Chain of Memories was remade for the PlayStation 2, titled Kingdom Hearts Re:Chain of Memories. It was developed by Square Enix's fifth Product Development Division, based in Osaka,[49] and released as the second disc of Kingdom Hearts II Final Mix+ in Japan on March 29, 2007[5] and as a standalone title in North America on December 2, 2008.[50][51] It has not been released in Europe or Australia for the PlayStation 2, but has seen a worldwide release as part of Kingdom Hearts HD 1.5 Remix. The remake includes polygonal 3D battles and worlds using the same graphics as Kingdom Hearts,[52] as well as voice acting and an improved soundtrack. While the card-based battle system and room synthesis aspects of the gameplay stayed mostly the same,[53] there were additions, such as the "Reaction Command" function from Kingdom Hearts II.[52] Voice-acted scenes occur only in Castle Oblivion, as well as in the Destiny Islands and Twilight Town simulations. The remake also includes new cutscenes and battles that were not in the original game.[54] IGN ranked it as the 92nd best PlayStation 2 game. The staff felt that it stood out among other card-based RPGs.[55]

Like the first Kingdom Hearts, Chain of Memories was adapted into a manga by Shiro Amano, following the same plot as the video game.[56] It was serialized in Square's Monthly Shōnen Gangan in Japan, then released in two volumes in Japan and later in the United States by TOKYOPOP. The first volume was released in Japan on October 22, 2005. A year later, it was released in English on October 10, 2006, followed by the second volume on February 6, 2007.[47][57][58]

The manga series has had moderate success. The first volume was ranked 112th on USA Today's "Top 150 best sellers" during the week of its release.[59] IGN praised Amano's renditions of the characters and the humor added into scenes. They also commented the weak elements of the game lessened the manga's overall quality.[56] The series was followed by a third manga series, Kingdom Hearts II. The Chain of Memories manga series was re-released in a boxed set in the United States on October 9, 2007.[60]

In September 2012, Square Enix announced Kingdom Hearts HD 1.5 Remix a compilation for the PlayStation 3 to include both Kingdom Hearts Final Mix and Re:Chain of Memories in high definition and trophy support. Additionally, the collection includes HD cinematic scenes from Kingdom Hearts 358/2 Days. It was released in Japan on March 14, 2013[61] and in North America on September 10, 2013.[62] Releases on September 12, 2013 for Australia[63] and September 13, 2013 for Europe[64] marked the first time Re:Chain of Memories was available in both of those territories. This version was later ported to the PlayStation 4 as part of Kingdom Hearts HD 1.5 + 2.5 Remix, released in March 2017.[65]