The only problem with the idea is that the eye can never move unless the generator is moved to a different area because the generator is the source of it's power and that would be impossible if the eye swallowed up the cocytans because there would be nobody to move it.
Also, the light bridges from the spires are necessary for it to function, as is some sort of crystal that is only briefly shown in the game(Light bounces off of it during the cutscene where the eye is activated and hits the actual eye and turns it into the solid crystal with a doorway)
Oh and the moons don't have any names. It is never mentioned in the strategy guide, novel, nor game, but making up names for them for a fangame is a good idea.
A prequel would be a tad bit pointless considering we all know what happens to the cocytans, unless it was before the creator made the eye but then what would it be about? They lived pretty much normal(Well, for a cocytan) lives up until the creator invented the life crystals and the eye.
"I am not afraid of you, you hairless monkey."~Ludger Brink