Kingdom Hearts/Hollow Bastion

Hollow Bastion is, unlike most other worlds in the game, not based on a Disney film. However, some similarities can be seen when compared with the Beast's castle from Beauty and the Beast and Maleficent's castle from Sleeping Beauty.

Losing the Keyblade
From where you start, jump on the floating platforms to get higher. Gliding will make it all much easier. Be sure to watch out for constantly moving platforms. When you get high enough, a cutscene will show Riku conversing with the Beast. After the cutscene, Riku will take the keyblade away from Sora and Donald and Goofy also leave Sora, remembering their mission - stick with the Keyblade Master. Sora will then partner up with the Beast to try and get into the castle and save the ones close to them. Your weapon will now be switched to the Wooden Sword and your only party member will be the Beast.

Getting the Keyblade Back
The path should be obvious from here. Keep using the platforms to get higher up. Eventually, you'll reach a single platform with nowhere else to turn. Keep moving forward to see the path marked as Castle Gates, and an elevator will be called to get you there. It takes a while to defeat the Heartless with just a Wooden Sword, so it's best to leave these to the Beast. Go down the stairs to the right of you and you'll come across a floating crystal sphere covered in lightning bolts. Examine this to call an elevator. You'll then end up to a place similar to where you started. Walk into the bubble on the right to teleport to another new area. Here will be a Save Point, a treasure chest, and a gate. Call Beast to the gate (the last option on the command menu) and he'll break it open. This reveals an area with another bubble. Walk into it to be teleported once again. This will reveal the puzzle of the Waterway. Go to the stone on the left and press Release. This will get one of the gates to move. Go forward and Release the next stone. From where you're locked in, go left and then forward for another stone to Release. The passage that you opened will lead to a stone on the ground. Release this to finally open the path to a bubble. Release the stone here to get the elevator moving, and Release the stone here to complete the puzzle. All that's left will be retracing your steps back to the Castle Gates.

The Library
After the battle with Riku and a cutscene, go up the stairs and straight to the middle. An opening will lead to a Heartless symbol with four missing pieces. You must find the pieces by completing various tasks. After finding all four, the door will open. The door to the left of the level leads to the Library, where Kairi's grandmother told her the story about the light. Here, you'll have to do something that can't be too difficult. In the shelves, there will be a small group of books that seem to stand out from the rest. This batch should all be the same color. Unfortunately, the many colored books are scattered. You must return the colored books to their correct positions, with books of the same color. The first book you should see is one lying in the corner, a red one - Khama vol. 8.

Completing the Puzzle
Go through the unlocked door and you'll find what it leads to - a higher level of the Entrance Hall. Next to where you enter, you should see a statue that, when examined, says "O mighty one...Show me your crushing power." Destroy the two pots on either side of it and the statue will sink a little into the ground. A cutscene will show a waterfall begin at the fountain in front of the Entrance Hall, on the base level. A piece of the Heartless emblem will come out of the waterfall. Walk a little further on this level to see a red Trinity mark in front of a statue. The three will push it, and the statue will fall to the ground and shatter. This will reveal another piece of the Heartless emblem. Move forward to a statue against the wall. There will be a statue that looks like the head of a beast. Light the torches to either side of it. There will be about two more statues where you'll have the same objective. The fire on the chandelier hanging in the middle of the room will go out, and you'll be free to snatch the emblem piece there. In between the first and second beast heads, there is another statue. It must be pushed to show a treasure chest on the lower level (the level between the base and the highest level). Inside the chest will be an emblem piece. Bring the emblem pieces back to the emblem in the middle to complete the puzzle.

Maleficent
After you put all the pieces of the puzzle into the Heartless emblem, the door will open. Go back to the Waterway and go through the door leading to the Lift Stop. Take the lift up and exit through the passage near the red crystal. You'll end up back at the Castle Gates. Many flying Heartless will attack you. Be careful not to let them lead you off the platform you're currently on, since this will bring you back to the Waterway and make you start all over again. Go around the corner and Examine the red crystal. Jump on the lift you just activated and wait until it reaches the other side, where it meets another lift. Glide to the other lift and then glide to a platform from here with a blue crystal on it. Examine the blue crystal and you'll be taken to a new area. Head up this area and Examine a red crystal. Afterward, head through a passage that leads back to the Lift Stop. Here, activate a blue crystal to be brought up. Head through a passage leading to the Great Crest. Go to the right to see a blue crystal, which should be activated. Go the High Tower from here and use a red crystal to move the block down. Turn around and go through a passage leading back to the Lift Stop. From here, go through the other passage leading to the High Tower. Examine the red crystal to lower the other block. You will now be able to head to the Castle Chapel, where Maleficent is waiting.

Another boss battle with Maleficent will follow this one, so be prepared to fight and place items like Ether in your inventory.

After this battle, prepare yourself for yet another boss fight.

Riku
After the battle, many important cutscenes will follow. After the last one, you must control Sora in a new body - the body of a Heartless. Go back to the passage that leads to the Lift Stop. Keep on going down and falling off ledges until you end up back at the Entrance Hall. After more cutscenes, you'll end up back at Traverse Town.