The Zone is a very complicated system of traps, and they're all deadly. I don't know what's going on here in the absence of people, but the moment someone shows up, everything comes into motion. Old traps disappear and new ones emerge. Safe spots become impassable. Now your path is easy, now it's hopelessly involved. That's the Zone. It may even seem capricious. But it is what we've made it with our condition. It happened that people had to stop halfway and go back. Some of them even died on the very threshold of the room.
But everything that's going on here depends not on the Zone, but on us!
So it lets the good ones pass and kills the bad ones?
I don't know. I think it lets those pass who have lost all hope. Not good or bad, but wretched people. But even
the most wretched will die if they don't know how to behave. You have been lucky, it just warned you.
"Stalker", Andrei Tarkovsky