I very much dislike how there is like a time limit of how long you can play as either Sora or Riku before you drop to the other character. I recently ran into this problem with the last boss battle I had. My drop gauge ran out during a boss battle and I had to restart the fight. .-. Another thing I wish this game had was more worlds. I only see 3-4 other worlds besides Traverse Town. Sure they made each world huge enough to explore, but I wish there was more variety...

with Rinzler, who turns out to be 

  

    
    Spoilerception    
    
  

  

  
Tron after he's lost his memories

Once you leave Traverse Town for the first time, you go to the first set of worlds. After those, you get another 2 worlds to explore, both of which are massive. The harder of the two worlds 

  

    
    Soundtrack spoilers? Yes    
    
  

  

  
Doesn't have music at the start, but when you enter the real exploration and fighting part of the world, there are no voices, but the music is fantastic
. Beyond that, there is one final world (from what I can see).

 Organization XIII characters come back as normal people, Ansem, Xehanort, and Terranort

Remember Chernabog from KH1 and how he just completely destroyed you the first few times you fought him? Or is that just me? Anyway, he makes a triumphant return in 3D in the Sorcerer's Apprentice world right near the end (or at least in Riku's story from what I know so far). I beat him on the first try, but "barely" would be putting it modestly.

Once you reach the second world, there's an item you can buy called Drop-Me-Not, which refills your Drop gauge by half and changes the drop speed to 0.8. Adds roughly another 10-20 minutes time before a forced drop.

Is it just me, or is Sora more magically-inclined while Riku is more physically-inclined in battle? It also seems much easier for me to battle as Riku for some reason, while I often have to level Sora up to just get ahead with him.

If the Sleeping Worlds are worlds that were consumed by darkness, yet didn't make it back to the Realm of Light after Ansem's defeat, then when did Traverse Town fall into darkness? If what Joshua said was true, and he created it out of the dreams of those from destroyed worlds, then how did gain physical form in the first Kingdom Hearts game?

Joshua said that when Rhyme and Shiki found Beat and Neku respectively, he said that Rhyme and Beat's timer didn't match up, nor did Shiki and Neku's. He thought the two Traverse Towns were parallel, but after thinking about it, he said they are two completely different worlds. What could've happened is Joshua created one of the two Traverse Towns, not knowing there was already one, and Shiki and Beat (or maybe Rhyme and Neku) ended up in the Traverse Town that Joshua didn't create.

Without any real explanation, Traverse Town fell to darkness in between Kingdom Hearts Chain of Memories and KH 2. Thinking back, I noticed you couldn't go to Traverse Town in KH 2, so it might've fallen to darkness during the story of Chain of Memories and there is some story behind it we might find out about later.

After beating the final boss as Riku which is 

  

    
    The final final boss    
    
  

  

  
Nightmare Armored Ventus,
 you find yourself on Destiny Islands. Riku looks around and finds Roxas, Ventus, and Xion. All of them ask Riku one question at different times. Just like at the start of KH1, you are given 3 answers to choose from for each question given. After answering each of their questions, Ansem the Wise appears to say he wishes to apologize for what problems he caused in the past. Riku asks Ansem how to wake up Sora, and Ansem says answering the questions of Roxas, Ven, and Xion woke Sora. Riku awakes from Sora's dream to find Sora, Donald, and Goofy having a tea party (of all things). Yen Sid says the Mark of Mastery exam is over and he is ready to name the next Keyblade master. He names 


  

    Spoiler Alert:    
    
  

  

  
Riku
 as the next Keyblade master, who seems surprised that he became a master, while his friend is excited and congratulates him for becoming a master. After which, Lea says he's there to learn to wield a Keyblade. He holds his hand out like Sora or Riku would, and a Keyblade of his own appears.



After Sora, Donald, and Goofy say goodbye to Riku and Mickey, the credits roll. Midway through, you have a dive-esque mini-game. If you collect all the golden letters in the names, you get the Secret Message in under your Reports menu. The message says 

  

    
    Try to decode it    
    
  

  

  
The past will be reawakened

as a new number

in never-before-seen detail



Prepare yourself for the awakening

of the next number

The sleeping worlds are ones that fell during Ansem Seeker of Darkness's conquest of the worlds, so it had to fall before Ansem was defeated. The only logical explanation is that it fell right when Sora opened the door to the fallen Destiny Islands

Why exactly is Mysterious Tower a Sleeping World? If it fell to Ansem, but didn't reappear after his defeat, how would everyone be there talking to Yen Sid before the beginning of the Mark of Mastery exam?

That was a flashback before the exam. They didn't slip into the Realm of Dreams until after defeating Ursula's phantom and finding the keyhole underwater. Mysterious Tower isn't a sleeping world.

You actually go to the Mysterious Tower and meet Mickey as the Sorcerer's Apprentice. It's in the second set of worlds.