Speaking with 4gamer, Lightning Returns: Final Fantasy XIII director Motomu Toriyama talked a big more about how the "world driven" game works. The Final Fantasy XIII team reiterated that FFXIII was "story driven" and FFXIII-2 was "player driven".
Lightning has 13 days to save the world in Lightning Returns: Final Fantasy XIII. While Lightning tries to change the future, the world moves at its own pace with a 24 hour clock and day/night cycle. Toriyama said "time management" was one of the key systems in Lightning Returns.
Players might not even make it to day 13 because Lightning’s actions can slow down the world’s demise or speed it up. Battle Director Yuji Abe says in-game characters act on their own schedule and there are different events depending on the game time (morning, afternoon, evening, or night), which changes in real time. Square Enix is still adjusting the time of one Final Fantasy XIII day, but Abe says he thinks it will be between 1-2 hours.
Abe hopes fans will discover new events when they replay Lightning Returns: Final Fantasy XIII and players will talk about what they saw during a run through the game. Toriyama said the foundation of Lightning Returns is the world driven concept and like a Daruma otoshi toy (a game where you smack the base of the Daruma with a wooden mallet) each part of Lightning Returns is a different block on the Daruma. Toriyama said he will explain his philosophy for the game design during Game Developer’s Conference which sounds like the next time we’ll hear about major developments in Lightning Returns.