by Robert Boyd
Perhaps a larger assortment of items, of varying utility. For example, some items would be of proper use and name, while others would be gimmicky and nonsensical.
I didn't play the Xbox360 version, so I don't know if you already have these, but a Gallery and Sound Test mode where you can see concept art, the various trailers, listen to the music, etc. If you could make them unlockables that you gain access to as you progress through the story,all the better.
A New Game+ of some sort, where you start over with your data from your endgame save, or maybe a secret dungeon, or if you can get permission, make whoever the $750 backer was a secret unlockable party member, or tie in the $500 backer's story as a sidequest (or as a parallel, shorter main quest for the New Game+ version?).
An unlockable easy mode, maybe? Kinda like Mega Man Legends 1. You only unlocked it after beating hard mode(Though, maybe that isn't needed here... Just the idea of unlocking it after beating it). Sort of a way to show the game you've mastered it.