This introduction is to bring you up to speed on the history of Sora and the gang, if the beginning of their story is unclear or you are not familiar with the first game in the series. While beating the first game is certainly not necessary, it may make certain scenes in Kingdom Hearts: Chain of Memories far less confusing. The good news is that this game really allows you to jump right in and play without feeling super confused.
The series started with the original Kingdom Hearts weaving together the story of three friends: Sora, Riku, and Kairi. These three, along with several other friends (who are also characters from several other Final Fantasy games) live on some prime real estate in the world of Destiny Islands. The good times are rolling until their homeland is devastated by an invading army called the Shadow Heartless. During the invasion, Sora is separated from his friends.
While Sora’s home world is being “forcefully reformed”, to put a happy twist to the reality, Sora finds a Keyblade. Pretty interesting coincidence, since it is the only weapon that can combat the Heartless—creatures of darkness that literally do not have a heart. Only a creature devoid of a heart could be so cruel as to destroy something as relaxing and coveted as a tropical paradise.
Sora winds up in another world, called Traverse Town, and comes face to face with Donald Duck and Goofy. Their meeting was also no coincidence, as the two Disney characters were sent by King Mickey to find the wielder of the legendary Keyblade. After their intentions are discussed, the three team up, making a motley crew of sorts. They depart for other worlds in the Disney universe, tasked with sealing each world’s “Heart”. They must carry out this task before the haters of hearts, in the most metaphorical sense, invade those places as well.
Turns out that a fellow Disney character, Maleficent, is pulling the strings. Her plan is to encapsulate the worlds in darkness by opening the door to Kingdom Hearts, thus using its power to rule the worlds.
Sora and friends eventually gang up and defeat Maleficent, only to find that she was a hired puppet herself, and Ansem (Xehanort’s Heartless) is the true villain here. Apparently, Ansem wanted Maleficent to open the door to Kingdom Hearts for him so that he could use the power to claim all the worlds for himself, by covering the worlds in eternal darkness.
Unfortunately for him, Sora catches wind of this and with Donald, Goofy, Riku, and King Mickey, they begin an epic battle that ends with Ansem’s defeat and the successful sealing of the great door to Kingdom Hearts. The good news is that peace is finally restored to the worlds and everyone can go back to their respective stories. The bad news is that someone should have told Riku and King Mickey to be on the other side of the door before it closed. The two heroically sacrificed themselves for the greater good, trapping themselves in the void of darkness. The continuation of the Kingdom Hearts series carries on straight into Chain of Memories.