There are some great guides but I thought I'd add one to address what I believe to be the most efficient approach to start the game off. If you want to 100% complete the game in the most efficient manner, you will need to complete the main mission on normal at least twice. After completing it the first time, you will have to play it one more time to mark all the targets. Accordingly, it is most efficient to get your S rank score & rescue the escapee during your first playthrough and get the cassette tapes and insignia when you mark the enemies. To sum up, the most efficient approach to the game is to play the main mission on normal only twice. Rescue all prisoners including the escapee to be executed in your first main mission playthrough and get an S rank. Mark all enemies and get all cassettes & insignia during your second playthrough without regard to score.
You may even get a negative score.
If you're playing with a guide, it is quite easy to get an S rank on the main mission during your first playthrough. The below video guide or narrative guide or both together can be used to get you an easy S ranking. If you use the guide(s) while you are playing, use the XBox button on your controller to pause rather than the View button
There are a maximum of 47,250 'fixed' points in the mission not related to time. That is almost enough for the S rank by itself:
No Combat Alerts 5250
No Kills 3500
7 Prisoners Rescued 24500
No Retries 5250
No Reflex 5250
Recover escapee 3500
Accordingly, we can take some time to reduce our exposure and ensure a relatively risk free approach. One of the keys to making this work is to get the escapee. It gets you an achievement and the escapee is worth double a regular prisoner--3500 points as a prisoner & another 3500 as an escapee.
Try to shoot the enemies from cover or from their side. At the start, press down on the D pad
to equip the stun pistol--we want no kills. Avoid the searchlight, climb up and shoot the watch tower guard from the side. Take the time to note an efficient shot. Using the regular reticle, aim for the head and shoot when it turns red. Since this is a low risk approach, you will be using the regular reticle at fairly close range. This has the advantage of making the shot easier as well as the red visual cue that is lacking in the long range reticle.
Drop down. Two guards are talking at the gate. Before they finish & move away, shoot the guard on the left. Wait for the other guard to notice. Shoot him when he stands over the first guard. This ensures that both guards will be hidden from sight by the barrier saving risk of discovery or the time it would take for you to move them.
Open the gate. Reload and proceed straight ahead until you see a guard. Crawl towards him and shoot him in the head. Stay low and proceed forward slowly until a guard appears looking away from you. Shoot him in the head. Go forward on the ground and look left shooting the guard in the head.
Taking out these guards ensures you have clear egress when you extract Paz. Turn around and take your first right. Jump over the fence to the left and go to the right corner where you find the escapee. Pick him up. Turn around retracing your steps to the gate you used to enter the complex. Place the prisoner outside the gate behind a tarpaulin on the fence. He will not be discovered and you can leave him there until you extract Paz. Reenter the gate and turn right hugging the fence until you come to a rock outcrop. Cross the street turn right and hop over the fence. Cross the road and enter the compound. Crawl through it using a big silo to get your bearing. You will want to scale the fence and cross the road to the right of this silo. An ideal place is to go between some porta potties to the right of the silo. Consult your map by pressing the menu button if you need to.
Once you cross the road, pop into the guard shack to get some extra stun gun ammo. Then proceed carefully down towards the POW compound hugging the wall to the right and staying down close to the ground. Use your binoculars to identify an enemy inside the compound and one closer to you. Shoot the one closer to you when he cannot be seen by the one inside the compound. If you can, conceal his body but only if the enemy inside the compound is at a safe distance and turned away. Use the mark on the compound enemy to take him out when convenient. Continue around the compound and take out the enemy near the gate. If you are in doubt, crawl so that you can approach him safely.
Open the compound. The prisoner on the near left corner is Chico. Leave him to the end. Take the other four prisoners to the nearest landing zone. Consult your in game map. There is a ridge that gets you there quickly and safely. After securing these 4, open Chico's cage. Skip the cut scene. The cut scene, skipped or not, causes 3 enemies to spawn near by. If this is your first time contacting either Chico or Paz, the following will unlock a few seconds after you open the cell door:
To reduce your risk leave Chico for the time being because you cannot crawl while carrying him. Leave the compound and mark the lowest enemy. Go above the ridge you used earlier. Staying on the high ground, crawl towards the two enemies just below you. Shoot the one facing you first and then the one whose back is turned towards you. Crawl forward and take out the enemy you marked as you left the compound.
With the enemies gone, you can call the helo. Go back and get Chico. Take him to the landing zone and put him down. Skip the cut scene. Leave Chico to the last and load the other 4 prisoners by pressing and holding the
button. A prompt will appear when near the helo. The reason you left Chico to the end is because the chopper leaves when you load him and you needed to have everyone else aboard first.
Now, go back up the hill hugging the wall to your right. Crouch or crawl when you see a guard leaning against a barrier and a truck. The truck driver will go towards the guard, pause a while and then leave. As soon as he gets out of sight, take out the guard behind the barrier by pressing
when near him. This pulls him over the barrier and ensures he will not be seen by the driver getting in the truck. If you shoot him, there is a chance the driver will notice and come to revive him.
Jump in the back of the truck and crouch. On Hard difficulty, you will have to lie down but on Normal you can crouch. A cut scene triggers when the truck stops. Skip it. Ensure the guard to the right of the truck is facing away. Hop over the right side of the truck and enter the red door. Hug the left wall and take out the guard between the obstacles to your right. He will be facing away and you can crouch up to him and take him out with
Note the camera in the corner and when it is pointed in the direction of the red door you entered, hug the far wall and slip down the stairs. Crouch and proceed cautiously waiting at the bottom of the stairs for a guard to pass before proceeding behind him. Don't bother taking him out. Enemy disposition changes after you talk to Paz. Go straight and open the cage in the far left corner. This triggers a cut scene. Skip it.
Leave Paz and go back the way you came. Crawl up the stairs towards the point where you slipped behind a guard a moment ago. Go forward enough so you can see a guard facing you. He cannot see you. Take him out. Shoot the other guard who will have his back towards you as he tends to his comrade. Turn left where the guards are and then hug the left wall behind some tanks. Get between the far side tank and the one next to it. Wait for the first of two guards to pass. Shoot the other guard in the body
. The first guard will notice if the other is incapacitated with a head shot. The body shot causes the guard to pause. You can then take him out with a head shot.
The first guard will pause as he takes stock of the two incapacitated guards you just took out. Crouch behind him and take him out with
. Go back to Paz and retrace your steps up the stairs. Mind the camera and wait till it is pointed in the direction of the red door. Proceed cautiously because there will now be an enemy on your side of the red door. You can take him out but it is less risky to just let him go up the stairs to the left as you use the cover between you to hug the wall to your right and sneak past him.
Exit the red door. Go past the open garage door and take a right at the corner of the building. Use your binos to mark two enemies to your left front in the corner. You will be taking them out. Hug the wall to your right and take a left at the end. When the enemies get close enough to get a good sighting in the normal reticle. Take out the enemy to your left whose back will be towards you. Take out the other enemy as he moves forward to check on his friend causing his back to be towards you. Hug the fence to your right and exit at the first opening. Call the chopper to the nearest landing zone. This is the one right where you started the mission.
The way is safe because you took out the guards earlier. You can follow the red marks and one green mark to the gate. Exit and put Paz down near the landing zone. If the helo is already there, do not put Paz on the chopper yet. Instead, go back down the hill and grab the escapee. Load him onto the chopper. If this is the first time extracting him, you will get the following achievement even before the chopper leaves:
Pick up Paz and press
near the helo when the prompt appears to board the helo with her. Your score should be in the 80K range plus or minus depending on your time
. You have about 30K of wriggle room so you can afford some reflexes and restarts. As long as you get all 7 prisoners, even a mediocre run will get you a comfortable S rank score.
If this is your first time completing the mission, the following will unlock after the Skilled achievement. It may unlock immediately or after you get the rewards.
During your next normal playthrough, you will need to mark all enemies to unlock trials that are required for an achievement. You will have plenty of time to get the cassette tapes and insignia. Make sure you get Chico's tape #5 in the compound where Paz is held before you contact Chico because it will disappear. Note that the way that we approached the first playthrough, we will have already gotten Chico's tapes #3 and #4.