The official Japanese website for Kingdom Hearts 3D: Dream Drop Distance was updated earlier today. The update comes with several new videos, showing a more extensive look at the gameplay. I've posted a video containing all the videos compiled into one above, but you can also check them out on the site itself (the ones on the site include the bottom screen as well as the top).
The game takes elements from past games, notably the newer command deck system from Birth By Sleep on PSP and ReCoded on DS. But it introduces a few new mechanics as well. First of all, there's the free-flow action mechanic, allowing for far more acrobatic moves (wall jumping, pole swinging, rail grinding, etc). New creatures called Dream Eaters appear as both allies and enemies, allies being called Spirits (your primary partners) and enemies being called Nightmares (the primary enemies you will fight). You can collect different spirits throughout the game and they will aid you during combat, as well as provide new special abilities for Sora and Riku to perform. There's also a "Nintendogs" like mechanic where you can raise your Spirits and care for them (seen in the AR-like game). Another new addition to the game is the drop bar, which acts like a slowly depleting timer. When it empties completely, control will switch to the other playable character (Sora or Riku). This mechanic could also be triggered manually without waiting in the Jump Festa demo playable last month.
Unrelated to the site update was the confirmation of a new world, one based on the movie Fantasia. It was revealed in the latest issue of V-Jump magazine and shows scenes from the famous Sorcerer's Apprentice sequence from the movie. The world is titled "Symphony of Sorcery".
Kingdom Hearts 3D is a completely new game in the series, continuing right after Kingdom Hearts 2 ends and setting up the events for the eventual and inevitable Kingdom Hearts 3. Sora and Riku enter sleeping worlds to help restore them, and prepare for another battle with Xehanort. They enter these worlds also as a means of taking the "Mark of Mastery" exam under the supervision of Master Yen Sid, in order to become true keyblade masters and unlock even more knowledge and power. The game has completely new or redesigned worlds and is developed internally as a major new entry akin to a numbered title by the Osaka team (ala Birth By Sleep). Kingdom Hearts 3D will be releasing on the Nintendo 3DS in Japan sometime during the month of March 2012. A US and Europe release is already planned and arriving sometime this year as well.