Not a bad idea in the slightest, could make it a prequel and it shows the events leading up to him ultimately going into the Tower. All up in the air but still lol
true but you could make it in into the sequel game to but it could show how everything happened on how he got trapped in the tower and how he escaped but also leaving it open to roam around freely afterward but could you add some sort of skill tree with passive skills in the current game and the might be a limit to how far down it can go