The online retailer has pencilled the title in for a March 29 launch, despite previous reports that the game was only 30% complete.
Square Enix has since denied the claims, according to CVG, but confirmed that the title will release at some point in 2013.
Announced during a Final Fantasy anniversary event, the game will take place during the last 13 days before the end of the world.
Featuring Lightning as a sole playable character, each in-game day is said to take between one and two hours of real time.
Time can be increased or decreased based on the player's actions, with even the possibility of ending the world before the 13-day limit. As such, the game is meant to be played multiple times and will not take dozens of hours to complete.
Square Enix also revealed that though Lightning Returns takes place many years after the events of its predecessors, the characters from Final Fantasy XIII-2 will return and won't have aged. Specifically, Hope is mentioned as offering guidance to Lightning through wireless communication.
Lightning Returns: Final Fantasy XIII will be released for Xbox 360 and PlayStation 3.
> Digital Spy reviews Final Fantasy XIII-2
Watch Square Enix's Yoshinori Kitase announce Lightning Returns: Final Fantasy XIII below: