Zero Warning is a 3 chapter campaign that takes place on the same giant mountainous level in each part. The first chapter sets you towards collecting gas from a barn. The second chapter is a run back to essentially the beginning of chapter 1 with Hard Rain's storm in effect. The third chapter, the finale, has you run to the docks, hold out against several waves of infected & tanks, and then (as the uploader's description says) run to a randomly designated evac spot for a chopper.
The campaign is very beautiful but one-note. There's few distinguishing landmarks (CEDA van, the docks, the barn safe room, the attic saferoom). Everything sort of blends together in a repetitive set of dense forest, swamped areas, mountain ridges, bridges, statues, and cut & paste houses. By the time I completed the first chapter, I was already bored of the visuals, and the storm mode & daybreak in chapters 2 & 3 were not enough to mix this up.
During each chapter I was plagued by the "purposeful design" of the level being confusing and disorienting, getting easily lost or turned around. There are multiple points where you're presented with branching paths that end up joining to the same area. This makes it incredibly easy to get turned around, even with lightposting. The repetitive visuals and lack of landmarks don't help matters, and even though each chapter shares this same map, it wasn't enough to get me familiarized.
The finale was very inconsistent. The docks holdout is a fairly open area with infected only coming from one direction, the chokepoints being minimally covered or obscured. This ended up with the survivors having very little trouble dealing with the waves of commons, specials, and even tanks. However, once the helicopter arrived, it was placed far away, meaning a run through endless hordes and tank spawns. And due to the confusing navigation embedded in the design of the map, it was altogether extremely difficult and unpleasant to make it through to the chopper.
I can see a certain type of player that would like this sort of experience. However, it's definitely not one for me, and I know if I played this with friends, the end result would only be frustration for everyone.