Well we can guess it will take place in a prison, and if I'm not mistaken the Priest from the winters run strike had escaped from said prison. Also cooperative and multiplayer was said so it could possibly be 2 fire teams competing to escape this prison. Now for the prison itself maybe it's a maze that can change its own order (the awoken are mysterious so we do not know what they are capable of), this could also mean portals to other areas or even dimensions. This mode would take fast thinking, skill and teamwork, obviously there will be enemy's to keep you company as the prison is occupied by the most dangerous of fallen.