Pripyat in the BBC film - comments..

I noticed that the kindergarten passed by MO and squad of loners, during MO's first visit to Pripyat, just before the underground carpark, still had a room full of beds with their sheets and pillowcases still on, as if their occupants had just got up from a sleep in the day.

The roads etc in Pripyat  have trees growing in them, and mutated branches with extra growth at the top, and larger leaves. If this is affecting the population, it could lead to larger animals in this fantasy game. Lynxes are it seems quite common and a lynx was the size of a lion, & the horses that were introduced could be wilder than they are at present. For even non-mutated animals such as the excellently modeled bear, are definitely scary for MO and NPCs.

So especially for players new to Stalker, the BBC film ironically shows the fantasy of Soup as the other reactors were started up again after a couple or more years. However this could be a benefit, for any DLC story where the processing is a factor.