Quote Originally Posted by LowCaloriePie View Post
I'd like to say this game is supposed to be their Master Qualification Exam thingy. Aside from the God awful title, the game looks pretty solid.
That's exactly what Yen Sid says in his brief line in the trailer. It is discussed in greater depth (SPOILER)in the secret ending to Re: Coded.

Kingdom Hearts 3D [Dream Drop Distance] takes place immediately after Kingdom Hearts 2. Nomura has called it the "prologue" to Kingdom Hearts 3. The title would seem to suggest that Sora and Riku are in some kind of dream during the game, which I suppose would explain why they're back to their younger appearances. At this point, it's probably a reasonable assumption that it is somehow part of their Master Qualification Exam.

Radiant Garden and Traverse Town are confirmed worlds, however no previously used Kingdom Hearts worlds will apparently appear in the title. Nomura has also confirmed that the bell tower from which Sora jumps in the trailer is from The Hunchback of Notre Dame, the first of the confirmed Disney worlds to be making an appearance in the game.