Then you've come to the right place!
After reading Plasmabender's test review, I realized that if someone is confused by Darksome Knights, then others probably are as well. So, here is a small (*snicker*) guide to the worlds of Darksome Knights. Specifically, I'll be covering Kingdom Hearts, since that's what Plasmabender was confused about.
Kingdom Hearts is a video game series by Square Enix and Disney. Because of this, most of the characters are from either Final Fantasy or Disney. The main plot revolves around Sora, a boy from a world known as Destiny Islands, who obtains a weapon called the Keyblade and journeys through worlds based on Disney movies with Donald Duck, a mage, and Goofy, a knight, looking for his friends, Riku and Kairi. Donald and Goofy are looking for King Mickey who left to deal with the villains of the series. In the worlds, Sora must use his Keyblade to lock the Keyhole which will seal the heart of the world and protect it from the Heartless, the main enemies.
While this is the main plot of the first game, it does get very confusing as the games progress. However, this is the main plot that Darksome Knights will draw from as well as the plot of Kingdom Hearts 358/2 Days, which I will explain now.
When Sora dies at the end of Kingdom Hearts, (oh yeah, spoiler) he becomes a Heartless and his Nobody, Roxas, was born. Nobodies are what's left of people who turn into Heartless. After Roxas is initiated into an order of thirteen Nobodies who want to become human again, they get a 14th member. The ttwo of them have to collect hearts to form Kingdom Hearts while Roxas has recurring flashbacks about the events of the first Kingdom Hearts.
Now if you want me to talk about the other worlds that are kind of confusing, leave me a message and I'll blog about it.