The video game S.T.A.L.K.E.R is happening in the Chernobyl Exclusion Zone, an area filled with super natural anomalies and artifacts due to the radiation. A legend/rumor says that there is a special crystal granting any wish at the center of the zone, inside the power plant's sarcophagus. The existence of the crystal can't be verified because a cultist faction, The monolith, is preventing anyone to reach the center.
https://en.wikipedia.org/wiki/S.T.A.L.K.E.R.:_Shadow_of_Cher...