Return to the Zone in S.T.A.L.K.E.R: Wormwood, a high-difficulty survival-oriented realism modification for GSC Game World’s S.T.A.L.K.E.R: Call of Pripyat. Wormwood builds upon the core Stalker experience, enriching the latest in the cult game series with brand new survival mechanics, intense and realistic gunplay, new missions, levels, fleshed-out building interiors and much, much more.
Excerpt from the companion article - 'Faction Overhaul: The Monolith':
"...several territorial holdings and cells were abandoned in the retreat from areas previously covered by the Brain Scorcher, leaving splinter groups disconnected from the main faction in the Zone's extremities. Despite this, so-called 'Death Trucks' are still known to operate under the cover of darkness - though much more rarely than in the earlier months of 2012."