Essential NPCs

== Quest givers ==
Most quest-giving NPCs are essential for the plot. If any of them dies, you will be softlocked. They have huge amounts of HP to not die accidentally, so you don't have to worry about it. A few of them (like Kostya) are even invulnerable.
When a quest giver dies, you'll get an annoying red beeping message all over your screen, so you won't miss it. At this point, it's better to reload a previous save. If you don't get the red beeping message on their death, it means this NPC is not vital for the rest of the game and his death can be ignored.
Do not abuse their huge HP pools by luring hordes of mutants to them; if they are not invulnerable they will eventually die.
If an essential NPC dies, you can resurrect him using a Living Heart artifact, if you have one. However, doing so will block you from getting S.T.A.L.K.E.R., the main achievement of the game. Besides, the artifact is rare and weighs 15kg. Reloading is probably the better option.
One NPC, Chemist, is initially dead during the Inferno quest, and you have to revive him (or choose not to!) with a Living Heart. It won't affect the achievement. This is the only initially-dead NPC that can be resurrected; there's no point in trying the Living Heart on other random bodies in the game, it won't work.
== Non-essential quest givers ==
Several NPCs are non-essential and won't give the red message on death, but still have valuable quests or offers, especially if you're aiming for the S.T.A.L.K.E.R.. If you want any of the following, watch them to not die accidentally.
* Docent Zagorsky in Ironworks - trader (some rare/unique items), quest giver (Detection sensors with a valuable recipe as a reward), and has a chain quest that is a part of The Secret Weapon of the Monolith questline.
* Sepator beyond his quest Perimeter defence, in Cordon. He has a great unlimited exchange of shotgun ammo, and a chain quest that is not a part of anything except the New Game achievement.
* Ivanhoe, if you saved him during Rescue "Duty" member. He has valuable cyclics, offering money for extra exoskeletons you don't need.
* Sergey the Shaggy, if you saved him during Rescue "Duty" member. He only has a single quest counted as a "chain" and still required for the New Game achievement.
Category:Core mechanics