First, let me start off by saying that this is an EXTREMELY ambitious attempt at a custom story, and that is something that we need to see more of, the level design we well thought out, and the premise was great. This map claims to be a horror story. It is not. This is a dark action adventure at best. While I think the idea of sneaking around volatiles is great, at no point did I feel that I was in any danger. At no point did I think I would screw up and send the monsters pouring after me, and that's where the horror element walked out the door with nary a goodbye. It does require sneaking, which is good, but there's no difficulty to that aspect, which is bad.

I thought the "Boss fight" with the big zombie was nice, and a good balance of combat meets puzzle solving, and raising the water levels to create a path for the survivors was genius.
But after getting to Rahim (Who is nigh unkillable) and being given a shotgun was anticlimactic. It seems like the ending was rushed, and didn't have much drive. This was the point at which you lost me. To be a horror experience, situations should be tense, and the gravity of the situation should be felt. The fun should be in avoiding death, and escaping your enemies, not walking predetermined paths to get a shotgun. (Try making the sewer more open with multiple ways to get around enemies)
Escorting the survivors was inconsequential, as all of the enemies were dead, and all form of challenge was over making the UV lights almost pointless ( Not to mention it hardly affected the Volatiles anyway)

My point is not to bash you, or tear you down, and I apologize if it sounds like I am, but this map simply did not deliver, and was underwhelming at the end of all things.

Instead of killing all of the enemies, add challenge to it by clearing the sewer but spawning enemies that randomly walk through the sewer, adding paths and shortcuts to get past them, or lure them with firecrackers scattered in some of the store rooms, all while trying to keep people alive. A situation like that would be tense, fun, and offer great replayability.

Furthermore; this game give you choices, but doesn't really capitalize on why that's important. Why is it bad to take the gun if no enemies attack the survivors? Maybe you could shake things up by making this a timed map, where leaving the gun would give you a longer time limit? There are many things that can be done to improve this, and this map definitely started off on the right foot, but strayed from it's path throughout it's course. It's not the worst custom version of something I've ever played, and as I said, it's very ambitious, which is very rare these days, but I firmly believe that you need to go back, look at the core elements of this map, and take a few steps to shake things up, and make it more immersive.

Overall, I give this map a 5/10.
Pros
-Level design was nice, smooth, and well thought out.
-Some zombie encounters were fun, and fulfilling, such as finding the axe held by one of the zombies through an optional tunnel.
-Big zombie "Boss battle" was intelligently set up using the environment as a weapon.
-Atmosphere was congruent to a zombie infested sewer.
-Environment interactivity was creative, and well thought out.

Cons
-Choices don't seem to matter much.
-"Horror" segments were boring, and lacked the pressure of a horror scenario.
-Ending was anticlimactic
-Saving everyone had no sense of urgency
-Rahim Boss fight is nearly impossible, with no negative repercussions if you shoot him and then return with the antizen.