Below is a section copied from a post from Global on Audible Play at DDAY. Hopefully this will clear up any concerns or misconceptions as to how this will work.
"Audible play basically gives us the ability to keep players on the field and force you to play to win all day and prevent collapse. The points and missions are determined by us prior to the event as well as where and when they are put into the game. The only difference is you don't know!"
I think this is a great addition to the game. For what it's worth those who tried it at Red Dawn mention it was some of the most fun they have at DDAy Adventure Park.
There is more information on the DDay site.