Here comes the regular outfit for the first game. Riku really upgraded his attire from back in the day. He's still sporting that yellow sleeveless shirt with a collar, but he has black borders with thin white inner borders. Oh my, we're getting complicated already. He has a vertical white stripe down the middle, but it's partially covered by two criss-crossing black pieces that have more white borders and a button on each end. And as if that isn't enough for one piece of his outfit, the entire back of his shirt is black, save for the mirrored criss-crossing pieces. He has two black wristbands, and two black gloves with white borders. Now get ready for a bumpy ride, because his pants are still a mystery to me. It's unclear whether he's wearing dark blue shorts or pants underneath those billowing bright blue (uh.. we'll just go with pants for now) pants, but I believe they're shorts, and you'll soon see why. He has a black belt, which presumably is attached to the white-bordered black pieces that connect to his pants. They have vertical black stripes down each leg, and they're held down tightly by two black belts on each ankle. His sneakers are now almost-real sneakers, with the reversed base colors of blue and white, black and grey soles, and yellow string-like things on the sides that connect to the two black straps. I don't think it's a matter of Riku being able to tie his shoes or not, it's definitely far more convenient to just slap on two pieces of velcro than to worry about tripping over laces and retying them. Wow. Makes you wonder if he got the whole thing specially tailored.
The next outfit arrives when Riku gets sucked into the darkness. All traces of the happy yellow color are gone, woe. He now wears a black & blue skin-tight full-body suit with a scale-like texture, which fades into red at his hands and brandishes a heartless logo on his chest. It also covers his entire neck. Collars are fine, but are they trying to choke him now? Geez. Moving on, his fingers and palms are covered by bright blue gloves. He also has three blue belts, two of which are criss-crossed to hold together what appears to be an off-white withering-wing-like frontless skirt. We assure you that Riku is not himself at this time, and that the one to blame for this strange addition to his wardrobe is none other than the game's creator. As we move along down, we can see two blue knee guards that meet up with the black & blue knee-high boots. ...Poor Riku.
Here come the two pseudo outfits I mentioned. They're just the previous two outfits in pixel form, for that lovely little game called Kingdom Hearts: Chain of Memories. Riku normally wears the regular outfit, but the magical appearance of dress spheres allows him to sport his dark outfit while in Dark Mode.
At the end of Kingdom Hearts: Chain of Memories, Riku decides he wants to steal a cool black hooded trenchcoat. And so he walks out of Castle Oblivion wearing this zippered cloak. It's difficult to see all the details, but there's a chain-like apparatus across the neck, and two silver things hanging at the ends of each hood string. This thing is full-sleeved, and equipped with matching black gloves and shoes. They're rarely seen, but he's actually wearing black pants. He also adds a black blindfold to the set. It's certain, though, that he isn't wearing a shirt underneath. Oh my.
As Riku pulls out another invisible dress sphere, his shirtless cloak combo from above magically transforms into another complicated outfit. His first layer is a black vest with silver borders along the zipper, which he leaves slightly unzipped on the top and bottom. The second layer is a white vest which is completely unzipped, and folds over to reveal a yellow interior, two slits, and several buttons. It also has a yellow border on the bottom, followed by an inner blue border. There are light lined patterns throughout as well. He has a white arm warmer on his left hand. Then comes the blingin' black and silver belt. Riku is back to being the king of fashion, ladies. Below, he wears baggy blue pants with two huge light pockets. And on his feet, he's finally got some normal gray and white sneakers, complete with black stripes and yellow laces.