Final Fantasy XIII-2 sold a total of about 3 million units across all platforms. This is half as much as the original Final Fantasy XIII. Yoshinori Kitsuke, a producer for the upcoming Lightning Returns: Final Fantasy XIII, seemed a bit confused as to why Final Fantasy XIII-2 sold less than the original. He came to the conclusion that players didn’t know that you didn’t need to understand the plot of the first game to enjoy the second.
“The reason for the drop may have been due to the fact that not many players knew you didn’t have to have played Final Fantasy XIII to understand the plot in its sequel. We’re hoping that we can get that message across for Lightning Returns, because the same is true here.”
The logic would probably apply to people who didn’t play Final Fantasy XIII, but what about the 6 million that did play it? If 6 million people bought the first game and played it, wouldn’t that mean that the same amount of people would buy the second game? Also, it’s worth pointing out that Kingdom Hearts II sold more copies in Japan than the first Kingdom Hearts game. And that game assumed that those who played it had already played the first Kingdom Hearts, as well as Kingdom Hearts: Chain of Memories.
Given the rather mixed fan response to Final Fantasy XIII, a more likely explanation is that half of the people who bought the game thought it was awful, and decided not to touch anything else related to it. Meanwhile, the other half either enjoyed the game enough to purchase Final Fantasy XIII-2 or thought the sequel would be better. Of course, we’re not taking into account all the used sales or rentals, so that number might be a good bit higher.
Or maybe people just want to play Final Fantasy Type-0 and Final Fantasy Versus XIII already. But hey, what do I know?
Source (http://www NULL.examiner NULL.com/article/lightning-returns-final-fantasy-xiii-producer-explains-declining-series-sales)