From a gaming forum thread on the atmospherics of loneliness and isolation:

In games that progress you in a linear fashion from area to area, sometimes you’re able to go back quite a distance through previous areas, although you’re not really expected to. In these games, there’s almost like an intangible sphere of “life” or “action” or “presentness” that you would normally follow, but you can go back to previous areas where it used to be but isn’t anymore. Previous areas where you’ve cleared out the enemies, solved the puzzle, met the new character, watched the cutscene, whatever... and there’s less than nothing left. If you were to go back to a very early area, it feels deader than dead. It’s still there physically, being correctly rendered and behaving as designed and all, but the intangible feeling of livingness has left it. There’s a very strong and foreboding feeling that you are not meant to be here. That you’re in a place “forgotten by the game”.

This seems like a relative of the phenomenon where you can sense that an area feels oddly empty as you explore it, and either you’ve been able to go there ‘too early’ for the plot, or you’ve found the remnants of something that was planned but otherwise largely cut, like the huge gate that will never open in Horizon Zero Dawn: a sort of digital Thomasson.