Alternative ending to Part 2
Takes place right after 'you' and Sasha figure out the weakness of the Fog.
TW for questionable ethics.
It is a devastating fact, but a fact nonetheless and therefore unchangeable. The two of you can't take the villagers with you as you escape.
As sad as it is, the people living here have no immune systems. It is Sasha, who tells you as much, as child of a doctor, they know more about medicine than you do.
They have asked several people and some of them don't even KNOW, what being sick means. In other words, the Fog keeps them healthy. Without it, they could die from a simple cold. Every sneeze could mean their demise.
Thus, you make the hard decision to leave them behind. You feel horrible, as you and Sasha drag Maria to the middle of the village, far away from the Fog and...let her go. The old woman, who immediately sets off towards the Fog, would need quite a few minutes to reach her final destination and this was hopefully all the time you need to flee.
Without bothering to grab your backpack, you quickly rush towards the thinning Fog, not stopping, no matter how much the biting cold cuts into your bodies, until you finally, finally, break through the last layer and stumble in the valley, that your home surrounds. Not looking back, you run up the steep hill, while the Fog behind you thickens noticeably.
After hearing your story and several experts from all around the world trying to penetrate the Fog with machines to no avail, the authorities decide to build a high fence all around the valley, letting it be guarded 24/7.
Should the Fog ever show signs of...starvation, or whatever you call it for this thing..., the same experts would try again to breech it and maybe contact the villagers to help them. Until then, it was decided to not give it new food or better breeds.
You still shiver at the thought of your future in this place hadn't you fled. It was enough to see the faint scars on your body, the last parting 'gift' of the Fog, that you would keep for the rest of your lives.
You don't know, what it was, where it comes from or why it did what it did, but you are just glad, that nobody else could fall victim to its voracious appetite.
Nobody...but the villagers you left behind to live yourselves. You will forever wonder, if you have done the right thing without getting an answer.