S.T.A.L.K.E.R.: Shadow of Chernobyl
The stalkers find it difficult to hunt for artifacts because the Ukrainian Military is in the area, trying to stop the zone getting bigger, and help control the mutant. The Military is an enemy of anyone who is not Military, and will work as a big team to attack anyone they see using heavy force and the use of Mi-35 Hind gunships, which are attack helicopters.