If we go into details about the setting, it is still vastly different from Stalker. The Zone in Stalker is only vaguely and mysteriously abnormal, in a subtle,

If we go into details about the setting, it is still vastly different from Stalker. The Zone in Stalker is only vaguely and mysteriously abnormal, in a subtle, mostly faith-based kind of way. By contrast, the Zone in Annihilation is very overtly supernatural, and in very specific ways that are important to the point it's trying to make - merging and recombining humans and the problems that face them, and manifesting internal struggles externally. To be fair, the Zone in Roadside Picnic, the novel Stalker adapts, is also more overtly supernatural, but still in a very different way. I really don't think it's fair to consider Stalker or Roadside Picnic anything more than inspiration for Annihilation.