I'm relatively certain that the 'unlockables' become 'availables' right after the 2nd act? I mean it sounds like its just progressive character development... almost like story telling rather than rpg'ing, hence the 'act-scene' format? the only difference being that the player controls all the in-between details like battles, trading, communicating, necessary things like that. Of course im going way out on a limb here and just piecing together what I can roughly make of the game.
According to some forums