The Cleansing Plan may not be true, but someone in the Eastern District must have proposed such a "once and for all" method. There is no wall in the world that is impervious to the wind.
Moreover, even if no one had actually proposed such an inhumane method, it's unclear now, given that the last method the People of the Eastern District used to show their dislike for the Western District People was to drive them to this cramped area of the Western District and let them fend for themselves.
People can endure to survive, but if they lose their lives, doesn't endurance become a joke?
So the Western District People must side with the Resistance Army.
Outer Zone Players are the same kind of props; the Cleansing Plan will never be understood or accepted by any normal civilization. Most players have normal emotions and will unconsciously side with the weak, not to mention they still need to clear levels. If the Western District ceases to exist, what will they use to clear levels?
