Heh you're totally right that making that would be like building a whole new game, but I can't help but still think it would make a cool special mode or something... But from the start I was very satisfied with this game with many wonders in it that we haven't seen yet so don't worry.
Maybe my first question early is a bit complicated so let me clarify: Did you have that concept in the past that you had to choose between it and the current game concept?
And now here's my new big question: If that concept had been used, what would happen to Killigan throughout his adventure? And what would happen to everyone else involved with him?