The only NPC that is allowed to be killed is the flamethrower user on the final level. All other NPCs and storyline enemies can either be knocked out, spared, ignored, or killed by friendly AI. If the player does mistakenly kill a single enemy not on the previously mentioned levels, they will have to start over with New Game. Reloading a save or checkpoint does not fix this . Regardless, it is possible to beat all levels without killing anyone, and a few players make it a point of personal pride to beat the game this way. Hints helping achieve this are listed below.
It appears that the damage is done to the player by a script during the railcart sequence, not by actual NPCs. The only enemy that is actually shooting at you is a machine gunner located at the last train car.
Crouching behind armor does not offer any protection and the entire section requires strict timing. The player needs at least four medkits out of five to reach the train. Exactly four are available at the end of the previous level in a locker and three more can be taken from the soldiers on the train itself.
Metal barrels and blue metal mesh boxes seem to be mostly impenetrable for enemy fire and can be used as cover. It is possible to shoot the soldiers once with a weak weapon to make them stumble and get a couple seconds to approach them safely as opposed to waiting for them to empty their magazines and start reloading.
Once the player crosses the square though the trenches, Artyom will be ambushed at the ruins of the State Historical Museum. The yard will initially appear to be desolated, but once Artyom approaches the gate, Pavel's team will reveal themselves. Pavel will demand to drop weapons over the loudspeaker, as he was ordered to take Spartans alive. When he recognizes the player, he says that general Korbut had a specific order about Artyom and tells the soldiers to execute him.
There are a few hiding spots available to Artyom in the museum, but the one behind wrecked cars on the right side seems to offer most protection from incoming fire. The Dark One will enhance Atryom's reflexes and will let him sense the soldiers through the walls for a short duration two times during the fight.
In about a minute four soldiers will enter the yard through the windows on the ground floor in groups of two. Just like during the Chase level, it is possible to shoot them once to make them stumble and make a safe approach for a takedown.
Once the group is dealt with, Pavel will using his sniper from the upper floor. You can either shoot him (as he can't die at this point) or wait until he gets bored. His weapon is the only one with the red laser pointer.
Once he gets bored or gets damaged enough times, he will order the remaining soldiers to open the gates and attack you. One of them is heavily armored and will actively approach Artyom, while the other two stay inside the gates.
It is required to shoot Pavel at the top of both stair cases and the end of the corridor to progress further. The snipers disappear once you get upstairs.
Stay crouched behind the barriers and let the AI kill everything, they are more than capable of defending the fortifications on their own. Once the tank arrives, you can use the spare fully upgraded Preved that lies next to the ammo box on the left side of the platform and shoot out the highlighted areas of the machine.
Riot shields will open up three times giving you a clear shot at the flamethrower soldier behind them. After enough damage is done, his fuel tanks will catch on fire and the resulting explosion will take out most of his protectors. Rangers will finish off the survivors.
After completing the final sequence, the ending scene will trigger and then your achievement/trophy will be earned.
- ↑ Steam community discussion (Russian): http://steamcommunity.com/app/43160/discussions/0/810924774462280131/#c810924774475899052