This reminded me of a dream I had a while back that I had after watching someone play Dying Light, which in turn spurred on this idea.
Players are given twenty minutes of daylight and must spend the day scavenging for supplies and materials to defend their temporary haven for ten minutes of night. During the nighttime, Turned have much more health and sprint.
A variant of this would be playing through three continous maps, and then spending ten minutes on the final level, fighting their away across a bridge and onto a dock before escaping on a boat.
The last part comes from a particularly vivid section of my dream where a bunch of dark silhouettes are swimming through the water and climbing onto the dock.
I dunno, maybe this is copying too much from WWZ.