Alright, so after a bit of playing for like...three weeks? Two? Decided to just up and make up two theories which could explain what has happened in this map. To the wiped out outpost, lab, town, and other such things.

To begin, we start off specifically around the area which has more forestation, either nearby a sign, in front of one of the phone dials, or by the hotel. Keep that in mind as I keep explaining further.
The player is able to go into the Hotel Rooms, where one is locked by default with a supposed paranoid survivor inside, and one which, once we enter into the bathroom of and find the covered corpse, causes the survivor's room to open by some means of something or someone breaking into it, killing the survivor inside. And once we check it out, it's already gone and or hiding in the backroom, where as we also find the corpse of the survivor who to me, doesn't look like they were stabbed or anything to that extent, but more so drained of blood.

Past that, nothing else occurs. Though it's obvious that the Player isn't alone.

There are now two options, either walk through the woods and head over to a nearby Watermill, or enter the town.

Nearby the Watermill are corpses, many of them. As the corpses themselves have flies audibly flying around them as if they have been decaying for a long period of time. However with that, by the watermill is a small shack which is locked and to my knowledge, cannot be open under by circumstances, I've tried to find ways to open it but just can't. Inside it however, we can hear what sounds like the call of something within.
Whatever is locked in there, is in there for a reason.

Past that, the Town holds a few things which could be considered points of interests. The first one, being the house next to the other which has a warning which just says "DANGER" on it. In the house itself, nothing appears to be too off aside from one thing, which is the painted figure of a man dressed in black, we'll call these 'Memory Marking' for a specific reason which I'll say later.

Besides all the other creepy things we find in the town, that is about it. However I do think that both the Watermill and that Memory Marking behold a connection.

Down into the laboratory, we find a lot of things which indicate that some form of experimentation was going on with something which could involve humans. With that however, including rooms which look to belong to children, where as another 'Memory Marking' can be found.
And down at the very bottom, we find what looks like a hole which leads down into an underwater floor that holds body bags and construction, where as we find another floor which is filled with water and body bags as well, and elsewhere, rooms which contain plant life, one with living plant life, while the other holds dead, potted plants.

Connected to the Laboratory, looks like what seems to be spots where people would go and hide, and by chance, plan things out. Much like Rebels. And above all that, the house which has the Memory Marking connected to the entire thing.

So to sum it up in short, I think whatever happened here was the possibility of new life being made within this town, life which involves the use of plants, water, and human DNA. Which overall, made what I assume to be Children of Plants.
Some of the agents working here most likely realized how ♥♥♥♥♥♥ up it was when the Lab began to experiment and basically torture children born from plants, so they took them up into their homes when the guards and scientists weren't looking, basically trying to give them some form of happier life.

Because of that, one of the Children who is most likely the leader, drew the Memory Marking within that house. But also for another reason.

However, something went wrong. One of the children escaped, going over to the Watermill and ending up being captured by somebody who most likely fed it blood. Which is why we see so many corpses within the Watermill.
And one after another, the Children grew because of the giant influx of water, and most importantly, blood. In short, they became not Omnivores, but Carnivores, running by the genetic coding of a plant which requires liquids to live and grow, which is why we see so much water, corpses, and blood. Basically vampires, to an extent.

And the only ones to which got out from there, are the Agents which treated them to a home which they were rarely given.

But yuh, that it, if you have your own theory, go nuts.

P.S, I'm writing this around morning time so my writing isn't the greatest and I probably rushed this. But regardless, you'll probably get the idea.