What is Final Fantasy Versus XIII you ask? According to wikipedia:
Final Fantasy Versus XIII is, according to its developers, a wholly independent story unfolding with different characters and a different visual design. Although it is set within the same Final Fantasy XIII universe, it is unrelated to any other entry within the compilation and is thus neither a sequel nor a prequel
So it’s basically a whole different game, but it has the Final Fantasy 13 name attached to it for some reason. I’m more excited about this game than FF13 though, because the team developing the game is the same team that made the two Kingdom Hearts games, which I love.
Also from wikipedia:
Within recent Japanese gaming magazine interviews, Tetsuya Nomura has stated that Versus XIII’s gameplay will be a realistic derivation of Kingdom Hearts battle system
The game is coming out sometime in the future, for the PS3