Creating a dynamic system for players to enjoy is hard enough, but when you have to account for all the variance in player choice, it becomes exponentially difficult to keep track of all possibilities as you add more and more content. Irrational's philosophical approach to this was to automatically assume the player was a psychopathic alcoholic who will absolutely act in a dramatically unpredictable way every time they played. This methodology allowed them to create key moments that didn't require the player's immediate attention, but wouldn't be lost because of it.