Sora, Donald and Goofy walk down a long path that seemingly goes nowhere. They see Pluto and start to follow him. He leads them to a series of crossroads. While deciding which path to take, a mysterious man in a black cloak approaches Sora and speaks to him, but at that moment his words are incomprehensible. The path becomes one and leads them to Castle Oblivion. The cloaked man appears as they enter the castle and gives them a card. They use the card to proceed through the castle. The first world they go to is Traverse Town, where they discover that Leon, Aerith, Yuffie, and Cid have forgotten all about them, yet they strangely remember Sora's, Donald's, and Goofy's names, where Yuffie comments, "You're not in my memory, but my heart remembers you." After Leon gives Sora a tutorial on fighting and gives Sora a Simba summon card, they leave Traverse Town.
The man appears once more after they arrive on the next floor. Another cloaked man appears and introduces himself as Axel. Sora battles him, and when Axel is defeated, he gives him more cards, disappearing soon after. Sora, Donald, and Goofy go through each floor, experiencing their memories, all of which are somehow distorted, each in a different way. They start to lose their memories. A Nobody named Naminé begins to replace memories of Kairi with fake ones of herself. It turns out she is good and is manipulating his memories under the orders of the head of the castle, Marluxia. This escalates to a final battle in the end, for Sora's life, and Naminé's freedom.
Meanwhile, Riku awakens down in the castle, and as he goes up the basement levels of Castle Oblivion, he must take control of the inner darkness inside of him, dealing with Ansem, the Riku Replica, and three members of Organization XIII; Vexen, Lexaeus, and Zexion, along the way.
Kingdom Hearts: Chain of Memories follows a totally new battle system as well as gameplay. The battle system now revolves around Sora's memories, represented as cards. Using these cards is the only way to attack. Map Cards are used to create rooms on each floor of the castle. What appears in each room depends on what card was used to generate that room. To obtain a map card you must defeat Heartless. Some map cards can only be obtained after getting further into the story for each of the different worlds.
Attack Cards - The most common way to attack, as the name suggests. These are depicted by different types of Keyblades and have red borders.
Magic Cards - Unleashes magic spells, such as Fire, Ice, Thunder, Cure, and Gravity. These have blue borders.
Item Cards - Used to restore Attack cards or Magic cards with Potions or Ethers, respectively. These can only be used once per battle, and have green borders.
There are three types of cards that are different from the other cards in battle:
Friend Cards - Appear in the battlefield at certain times for pickup and can summon an ally to help fight. These have green borders, like Item cards.
Enemy Cards - Based on enemies or bosses and can temporarily give Sora (or Riku) better offensive or defensive capabilities. These have black borders, and cannot be used in sleights.
Gimmick Cards - Gimmick cards only appear during certain boss battles. Unique attributes of these cards is that they are always green, the card value is always 0, and the picture on the card is a green Mickey Mouse insignia, like the keychain attached to the Keyblade. When used, the colors on the screen inverse, and the boss is either stunned, or the battle area changes allowing you to gain the upper hand.
Each card has a number from 0 to 9. This is known as Card Value. When a card is played against the enemy's card, the card with the lower value "Breaks" and is discarded. This leaves enemies vulnerable for a few seconds. Cards with a value of 0 can break any attack, but can be broken by any card if played too early.
A special ability that can be either learned from leveling up, or obtaining them from boss fights or chests. Some sleight examples are: Sonic Blade, Strike Raid, and Ars Arcanum. Some of these sleights did not appear in Kingdom Hearts, such as Fire (Blizzard, Thunder) Raid, Homing Fira (Blizzara, Thundara), etc., as well as some friend sleights, such as Blazing Donald. Further sleights were added to Kingdom Hearts Re: Chain of Memories as well. For more info on the game, search it in this wiki. For more info on sleights click the link above.
Cards can be combined into sets of three, not only creating a higher value combo that is more difficult to break, but is also essential in activating sleights. The cost of combining cards is that the first card used in the combo cannot be reloaded when the deck is reloaded, although certain items, such as Elixir and Megalixir, can reload any unreloadable cards.
Sora can use any available card to create up to three decks as long as there is at least one Attack card in his deck and you don't exceed his Card Point (CP) limit. During Level Up's Sora can increase his CP, in addition to obtaining more HP and new sleights at certain times. Other than using Attack, Magic/Summon, and Items cards, Sora can also use Premium cards, which are special Attack or Magic cards. These cards do not require as much CP to equip although they can become unreloadable cards when used, with the minor exception as the second or third card in a combo. Other than using Moogle shops to obtain additional cards, Sora can also collect cards by smashing or jumping on objects, occasionally making a random card appear. There are certain cases where Sora has to earn the card through the storyline first before it becomes available in a Moogle Shop.
There are cards throughout the game that are used to open doors to different rooms once entering a certain world. They are in the same colors as the Magic, Item, and Attack Cards, except they are usually only gained at the end of a battle, and they generally only are used to open the doors within world. They may have names such as Roulette Room, Tranquil Darkness, Feeble Darkness, Calm Bounty, Martial Waking, and even special room cards called Key to Rewards and many more. They are needed to open all doors throughout Castle Oblivion.
After completing the game as Sora, a new challenge arises. Reverse/Rebirth mode follows Riku as he climbs the basements of Castle Oblivion. Riku gets a World Card for each of the worlds Sora goes through except 100 Acre Wood. Riku's deck cannot be changed, however, it changes automatically as time goes on. Riku does not need as much time to reload his deck. Certain enemy cards are only available to Riku, and then unlocked for Sora after completing the game with Riku. Riku can only keep the enemy cards that are based on the bosses after winning them during battle, the others are available in one world only.
Instead of leveling up HP, CP or sleights, when Riku levels up, he can increase HP, AP (Attack Power), or DP (Dark Points). After Ansem, Seeker of Darkness (who is still alive) tempers with the darkness in Riku's heart, Riku can use his dark powers during battle. These powers are triggered by taking damage or breaking his opponent's cards; when the Dark Points reach 30 or more, Riku will automatically go into Dark Mode. In Dark Mode, Riku can use 3 powerful sleights exclusive to his Dark Mode: Dark Aura, Dark Firaga, and Dark Break (these attacks were used by the Riku Replica in Sora's story.) How long Dark Mode lasts depends on how much DP he has, and taking damage as well as being card broken reduces the amount of DP Riku has left in a given battle. When the DP counter reaches zero, Riku turns back into his original form. Dark mode can be achieved any number of times in a given battle.
Riku does not have access to any of the friend cards that Sora had. Instead, he has King Mickey as his only friend card. Using Mickey heals Riku, reloads the deck, and stuns enemies for a few seconds. Using more Mickey cards at once increases the power of this attack. Because of his inability of using magic cards, Riku cannot heal as easily during battle, limiting it to the Oogie Boogie and Search Ghost Enemy cards in addition to Mickey Mouse. Bosses exclusive to Riku's story are: Zexion (Re:CoM Only), Lexaeus, and Ansem, Seeker of Darkness.
Kingdom Hearts Re:Chain of Memories is a PlayStation 2 remake released in a package along with Kingdom Hearts II Final Mix. The game features 3-D graphics and voice-acting, along with all-new cards and cutscenes. It was released in North America on December 2, 2008. A PAL version was never released until the later HD release of the game that was part of Kingdom Hearts HD I.5 ReMIX.
Tarzan was unable to return for Chain of Memories and its subsequent remake/remaster due to Edgar Rice representatives denying Square Enix the rights to use Tarzan for Kingdom Hearts.
In Japanese, Reverse and Rebirth are homophones.
By holding the down button you can enable an event skip feature.
In Kingdom Hearts: Chain of Memories, Monstro and the 100 Acre Wood are the only worlds with minigames (Monstro is a battle oriented world though).
According to director Tetsuya Nomura, the game was originally going to be called Kingdom Hearts: Lost Memories.
Even though a gimmick card is a zero, the easiest card to break, a boss will never use a card to break it as it freezes time.
In the Hollow Bastion level, Belle is shown allegedly allied with Maleficent. Coincidentally, the Maleficent film is written by Linda Woolverton, who had written Beauty and the Beast, Belle's debut movie.