The factions of the STALKER series and the upcoming STALKER 2: Heart of Chornobyl are one of the games' greatest triumphs, with each group having their own understandable motivations and goals. While each faction has undergone changes in leadership and territory, only two have experienced real development: the Military and the Mercenaries.
Usually serving as mid or high-tier human enemies, members of these factions are a challenge to fight with loot to match. However, as is often the case in the Zone, GSC Game World has given these NPCs much more nuance and depth than simply being another target to shoot. In STALKER 2, their presence will likely have far-reaching implications not only for the Zone, but for the outside world.
Warning: The following contains spoilers for STALKER: Call of Pripyat.
The Military Faction
Before 2006 in the STALKER world, the Ukrainian State Security Service was a national army like any other. Nevertheless, no one could have been ready for this new Chornobyl; the first forces sent in were either lost to the mutants and anomalies of the Zone, abandoned to fight for their own survival, or routed to the edges of the perimeter. With the Zone now out of its control, the Ukrainian government locked down the exclusion zone and ordered that any mutants or unauthorized personnel be shot on sight.
By 2011 the Military was losing what ground it still had, not helped by rampant corruption as soldiers were easily bribed by Stalkers entering the Zone. Spetsnaz occasionally conducted missions in the Zone, but even these highly trained soldiers fared poorly. The military grew so distant that the sanctioned ecological teams stationed deep in the Zone started hiring Loner Stalkers skilled at surviving the Zone for protection. Ultimately the Military's successes would come from the very thing they had sworn to stamp out: Stalkers of their own.
In Shadow of Chernobyl and Clear Sky, the Military are enemies adjacent to the Bandits, albeit better equipped with superior tactics. Most military weapons are basic but reliable and their armor provides excellent defense against firearms but below-average protection against anomalies and mutants. Spetsnaz armor is also lacking, though they at least have high end Eastern bloc guns for STALKER players to bear in mind. The main exceptions to this are the suits worn by Military Stalkers, which are some of the best outfits available with high protection against all damage types.
The Mercenary Faction
The Mercenaries are a secretive and mysterious faction operating on hidden agendas and unknown backers. Much like Loners the Mercenaries aren't actually a unified faction, rather an umbrella term referring to privately-hired contractors with combat experience outside the Zone. However, their prolific use of Western bloc guns and their collective use of the falcon symbol hints at some form of central cabal pulling their strings from the shadows. All Mercenaries demand large sums of money or the Zone's rare and powerful artifacts as payment for their services
Individual mercs vary in loyalty and morals. Many Mercenaries view any Stalker observing their operations as a loose end to be tied up at the first opportunity, even in cases where the Stalker assists them in navigating the Zone. Others operate on a warrior's code, only choosing worthy employers like the Ecologists and avoiding unnecessary bloodshed. The player character of Clear Sky, Scar, is a Mercenary himself, allowing the player to choose their own loyalties in the ideological war between Duty and Freedom.
Mercenaries are one of the best-equipped factions in the Zone, using high-end Western weapons and explosives. Combined with their above-average battle-tactics and numbers, firefights against them can be tough at any stage of the game. Even their lowest-tier armor provides good protection, and their best units are equipped with anomaly-resistant combat suits or powered exoskeletons. It is even possible that NATO itself is their main backer, using proxy soldiers to bypass the black market supplied by Stalkers and advance their own interests in the Zone.
The Importance of the Military and Mercenaries
The Military and Mercenaries represent the mundane outside world and its instinctive desire to subjugate the Zone in the name of profit and the status quo, only to be rebuffed in the face of something outside of their understanding or control, yet for a long time refusing to learn from it. Both factions excel at hunting down human Stalkers yet constantly find themselves vulnerable against the threats of the Zone itself. Over the course of the games, this slowly changes.
The once dogmatic Military, following defeat after defeat, at last recognizes Stalkers as a potential asset, forming their own group of Military Stalkers drawn from or taught by ex-Loners. The most famous of these, Major (later Colonel) Alexander Degtyarev serves as the player character of Call of Pripyat, not only surviving but discovering and escaping with the deepest secrets of STALKER's Zone. By admitting their own ignorance and learning from their one-time enemies, the Military finally makes progress.
Conversely, the Mercenaries are shown to deepen their desire to exploit the Zone at the same time they are coming to comprehend it. In Call of Pripyat they have transitioned from extracting artifacts to pillaging the underground labs; these labs contain the means by which the Zone was first created. With the hints in STALKER 2's gameplay trailer that someone is trying to subjugate the Zone, it may be that the Mercenaries and their masters are about to become a much greater threat. Not just to Stalkers, but to the Zone itself.
STALKER 2: Heart of Chornobyl is in development for PC and Xbox Series X/S.