First time on the forum and i decided to sign up because of 2 posts that i have seen. First was about the whole 6th dimension thing and trying to get themselves out of a loop and the second was someone saying that the clock in the PAP room in kino goes backwards therefore showing a possibility that you are going back in time as the game progresses.
So i did a bit of thinking on this and to me it could explain why the zombies get stronger as rounds go by. In my mind i would think that the zombies would get weaker as time goes by since they have been around longer and are less fresh, so to speak, therefore as you travel backwards in time the zombies get fresher and therefore stronger.
Like i said its just a theory with no real evidence to back it up, but hey the worst thats going to happen is someone is going to tell me that i'm wrong and that i have no proof. But since i'll readily admit i have no proof its all good.