S.T.A.L.K.E.R.: Shadow of Chernobyl/Chernobyl NPP

Reach the power plant
Your starting point is on a bridge crossing the (now dried) canal. There'll be a blowout in approximately 10 minutes. When six minutes are remaining, you'll be given a warning and a timer appears.

Head west and north until you find a gap in the wall, where the train track runs through it. Go through and follow the road south and west, up the hill and over the bridge and down the embankment. Cross the train tracks to the northern side and keep moving west until you see an open door on your right, go in to the back left corner of the room to the next map.

Sarcophagus
Your starting point is in a small circular room at the northwest of the middle floor. When you move around inside the Sarcophagus you'll hear an ambient voice speaking. Move out of the initial room and head east – soon you'll notice a passage leading further south. Move into the next hallway proceed north and then east – soon you'll come to an opening to the north. Move further east, slowly head into the room. Move west into the hallway and follow that south until you come to a room with stairs going up. Up the stairs you'll find a doorway to the west; slowly make your way forward and go either left or right and clear out the place. Once done, you are now ready to move on – either to the Wish Granter or to the "secret door".

Wish Granter
The entrance to the area with the Wish Granter is to the south and should me marked on your minimap. Depending on what you've done during the game you may get different endings from the Wish Granter.
 * I want immortality: If you aren't able to meet any of the below categories, it defaults to the "immortality" ending.
 * I want the zone to disappear: If your reputation is above 1000, then you get the "good reputation" ending.
 * Humanity is corrupt, mankind must be controlled: If your reputation is below -1000, then you get "bad reputation" ending.
 * I want to be rich: If your money is above 50,000 RU, then you get the "money" ending.
 * I want to rule the world: If Lukash and Voronin are dead, then you get the "rule the world" ending.

The C-Consciousness Project
The "secret door" is located on the northern side of the floor – you'll find the entrance and a ladder near the rotating light. Once you've climbed the ladder you'll be prompted to open the door using the decoder. Approach the door and "use" it – a timer will start indicating that the decoding will take 30 seconds. When the door finally opens, proceed through it onto the level transition. Proceed forward to the south, going into a long hallway. Move east and then south. Eventually you should come upon the room before the control room. Move into the room, but don't head into the control room. You'll notice a number of blue orbs and above them a hologram resembling the monolith. You need to shut down the monolith so shoot the blue orbs. Once you've destroyed them all, the level will end. You'll see another hologram, this time representing a professor. Your final choice is whether or not you wish to join the C-Consciousness project.

Join the C-Consciousness
If you decide to join them, you'll be treated to a cutscene and the game will end.

Refuse to join the C-Consciousness
If you refuse, you're back outside in the Chernobyl area. Your mission is basically to escape, but to do so you'll need to head into a number of teleporters that will take you around the map. There are about 15 in total and you'll be facing opposition in most of the areas. Move ahead and you should be able to see a glowing orb up ahead, slightly to the right – that's a teleporter and you'll need to head through a number of these to escape. Run up and into:

You'll find yourself on the ground with a ladder just ahead; move up behind the large pipes and use them as cover. There are also soldiers on your right side, where you'll also find another ladder going up. Another ladder will be going up. Move to the east and you'll find a ladder going down; head that way and down the next ladder as well. You can find another ladder close by going up to a small roof. Move further to the east and you should be able to find yet another ladder going down to a somewhat narrow walkway. Proceed north. If you look west you should see a large "crane" and a large building behind it. Following the walkway you should soon spot another teleporter to the west. Proceed forward into:
 * Teleporter 1

You'll start falling and then head into:
 * Teleporter 2

Will lead you onto a small building on the roof, move towards the next teleporter located at the southwestern part of the roof. Entering:
 * Teleporter 3

You'll find yourself on another roof directly in front of a ladder – climb it. You are on a very narrow walkway. Move forward and down the slanted roof and up the ladder. You'll find yourself on another roof directly next to the exhaust, move into:
 * Teleporter 4

To the southeast. You'll fall into:
 * Teleporter 5

Onto some vents with a ladder ahead of you. Move up the ladder and into:
 * Teleporter 6

Which will take you to another narrow walkway; move ahead into:
 * Teleporter 7

You're on another roof, proceed forward and you should soon spot a place where the railing is broken. Move towards it and when you get close enough you should spot:
 * Teleporter 8

You'll find yourself on another narrow walkway, move ahead into:
 * Teleporter 9

You're now on another walkway with pipes on both sides, the walkway is broken up ahead and you need to get onto the other side of it. Ahead you should see a ladder on a building close by to the south – you'll need to get there, so jump onto the reddish pipe and onto the ladder or roof. On the western side you should find a very thin railing (or fence) – move onto that and jump onto the next roof to the south. Proceed east and jump down to the next part to the north. You should see a ladder going down and behind it the second part of the walkway that you initially started on. Move up to the ledge and jump onto the walkway. Proceed east where you should now be able to see:
 * Teleporter 10

You'll find yourself on the structure you've just passed under. Head north and into:
 * Teleporter 11

Next to the tall chimney. You'll find yourself on another narrow walkway with:
 * Teleporter 12

You’ll come to yet another roof, simply follow the roof, you'll soon come to:
 * Teleporter 13

Proceed east and you'll encounter:
 * Teleporter 14

Once you head into it you'll very shortly be brought back to Sidorovich, who makes a comment, and you'll soon after return to another roof near Chernobyl. You can just barely see the next teleporter from here, on an elevated area – but you'll need to head around the structure to find some stairs going up. You'll need to make your way to the south. Directly east of the starting point you'll find some stairs going up – you need to head up there to work your way to the south. Directly up the stairs, next to a container, you can find an Exoskeleton armor – take it if you really need a new armor, move south (you need to go south, west and then south again crossing a number of smaller buildings/structures). Eventually the elevated walkway will end – but there should be another structure just ahead that you can jump onto. You should now be able to make out the last teleporter in front of you, on another elevated area – there is a ladder heading up to:
 * Teleporter 15

You'll be treated to a nice cutscene. Congratulations, you've completed the game and explored the "best" ending!
 * Teleporter 16