Because until they made X-2, not a single one was a sequel.
Zapper - February 2, 2012, 8:16 am,
True, but then they went on to make XIII-2.
himitsutokumei - February 2, 2012, 1:33 am,
Actually, I researched that my senior hear in high school. They were starting to go out of business, so it was going to be one of the final game they made. It sold so well that they started making more.