Welp, I'd keep the music, characters, story, and the battle system. And also, I must be one of the few who liked having my party members chosen for me for most of the game. (Because I really suck at choosing and decisions.) So I'd like for that to be kept as well.

And get rid of the extremely long dungeons. I mean, usually I don't feel fatigued when I play a game for a long amount of time. But to continue going down a corridor forever and ever endlessly... it gets old fast and FFXIII is one of those few games I can't play for more than two hours. So less linearity, yes. And more NPCs as some had said. Back to the old FF tradition of cities with NPCs and also?

BRING BACK THE AIRSHIP.

Seriously. A free-range roaming airship where you can fly across all over the map. The last FF to do that I think was IX, so I'd like to see that again.

On the difficulty, I would like to see them even it out a little more. The game got really tedious and hard for me at around Chapter 10. It's like it jumps up all of a sudden and does not let up. So I'd like for them to make the game get gradually harder instead of the difficulty jumping up all of a sudden and 1,000 CP suddenly barely doing anything to level up your characters. Seriously, it was ridiculous how slow I leveled up when I got to Chapter 10.

Oh and I think they should cut down the size of Gran Pulse and allocate that to Cocoon cities.