Lightning Returns: Final Fantasy XIII will feature a pre-determined number of each monster when you start a new game, kill too many and they will become extinct (until you start a new game), but there’s an incentive for doing so.
Game design director Yuji Abe confirmed that players will be able to whittle down a monster’s population until there is only one of its species left (referred to as the “Last One”). Each “Last One” is a lot more powerful than its counterparts and, depending on the monster, may have different abilities. Defeating these powerful enemies will net you rare items.
Upon completing the game once on Normal mode players will unlock Hard mode. According to Abe, monsters on Hard mode will be stronger and drop higher level items. There will also be items sold in shops that are exclusive to Hard mode.
Lightning Returns: Final Fantasy XIII will take players around 20-30 hours to complete, but, according to Abe, if you trigger almost all events and don’t skip any scenes it should take around 50 hours.
The game is set to release February 11, 2014 in North America and February 14, 2014 in Europe for Xbox 360 and PlayStation 3.