Motomu Toriyama has shot off some details of the FFXII Demo that will be bundled next march with the Japanese version of Advent Children Complete.
IGN (linked above) has better translated the details and like the FFVII demo you will be able to play through the opening prologue and players will be able to control of more than Lightening only.
To quote: Describing the demo, Toriyama said, "Like the FFVII demo that was included with PlayStation's Tobal Nol.1, you'll be able to play from the opening through the prologue. We're making it so that players will understand about the world of the Cocoon and how the Lucys are handled."
Toriyama hinted that the demo could be of substantial length. While not giving a specific play time, he said, "We'd like to make it something with lots of volume." To this, he added with a laugh, "I think it will be longer than FFVIIAC."
As to what all that content will consist of, Toriyama wouldn't get too specific. He did confirm, however, that the realtime sequence that was shown in the DKS3713 trailer won't be included. That section of the game actually follows the demo, Toriyama explained, mirroring comments that were made by the development staff in a documentary film that aired at the event.
During the demo, players will be able to take control of more than just Lightening. The mysterious blonde-haired male character from the trailers will be playable as well.
Toriyama clarified a bit about how FFXIII handles its characters. There's no actual "main character" in the game. Players will experience the story from the perspective of multiple characters, something that he refers to as being a "new style." The demo will offer a glimpse at this new type of storytelling system. He considers players sampling the new system to be a major point for the demo.
The game's battle system appears to reflect this switching off of characters. The game's battle system is party-based, Toriyama explained. Players switch between characters as they fight. More PlayStation 3 News...