So here?s my walkthrough for the 2nd mission, called ?Deep in the Mines?. This is without any doubt the quickest (and perhaps the easiest) level from the whole game, last but not least because there are only 28 enemies ? which is by far the lowest number from any of the levels in IGI 2.
THE FIRST 2 ENEMIES
When the mission starts, the elevator which you?ve used in the previous mission will ride you down to the mining area. Your 1st objective is to access the lower part of the mines. This can be done either by riding an elevator or by going through a nearby ventilation shaft (you?ll use this 2nd option). But first, you?ll have to kill the 2 guys guarding the surrounding area ? one of them standing near the camera, and the other patrolling nearby.
As you?ll see, the guard near the camera regularly changes his position by walking slightly nearer towards the elevator (standing there for a couple of seconds) and then by walking back (stopping there for a long while). On the other hand, his patrolling buddy just constantly walks back and forth a long stretch, stopping at both sides of his patrolling route for a while. You?re going to kill this patrolling guy first. The trick is to kill him when he?s FAR AWAY from the other guy, preferably BEFORE he stops at the far end of his patrolling route. Simply, if you kill him somewhere in this dark area, the other guy won?t spot his corpse at all... How to do it? Just follow this approach:
When the level starts, immediately drop your primary weapon! If everything goes OK, you won?t need it in this level anymore (with one exception discussed later) + it will make you a bit faster. Immediately after you drop your primary weapon, hold down the forward key in RUN mode, so you could leave the elevator as soon as possible. Once you?re off the elevator, continue running towards the patrolling guy, who at this time starts walking to the right (i.e. away from the other guy). Of course, he?ll hear your steps if you go too close to him, so just run as close to him as you can without being heard, and then quickly switch to WALK mode (basically, you can run as far as the first lamp). Now continue pursuing him till you?re about to leave that cave corridor you?re in, and then immediately switch to CROUCH-WALK mode, otherwise the guy near the camera (who at this time RETURNS BACK FROM THE ELEVATOR) will spot you. You don?t need to use the strafe keys when going through that corridor (i.e. when using the RUN and WALK mode), because if you?re too quick, the guy near the camera will spot you. Anyway, once you leave that corridor, continue approaching the patrolling guy diagonally (this time with using the strafe keys), and as soon as that neck-breaking icon pops up, kill him. It may seem a bit difficult to master this approach at first, but a couple of tries will do the trick for you. If you keep the RUN + WALK + CROUCH-WALK approach (see this pic) & do it continuously (i.e. without stopping), you should have no problems to kill this guy before he stops at the far end of his patrolling route.
Now as soon as the patrolling guy is dead, quickly hide behind the nearby truck. Since the other guy at this time will only START WALKING TOWARDS THE ELEVATOR, you should?ve no problems to get behind that truck before he can spot you on his way back (you can even use WALK mode when going behind that truck, if you want). Now once the guy returns back (use the peaking to know this), he will stand still for about 20 seconds, so use this time to open the doors leading to the ventilation shaft, and then hug this nearby wall. At this time, the guy will be ABOUT TO WALK TOWARDS THE ELEVATOR again, so get close to him as you can whilst being close to that wall (by doing this, he won?t have a chance to notice you), and then use the peaking to know when he returns back from the elevator. Once he?s back, quickly approach him in CROUCH-WALK mode (using strafe keys, of course) and then break his neck. If you did it as described, the camera above will be turned (or will be still turning) TOWARDS elevator, and thus it won?t notice the killing at all. Once again, if you did this whole approach as described (i.e. without any interruption), you should have absolutely no problems to kill this 2nd guy. It just requires a couple of tries before you?ll get fully accustomed to it.
Alternatively, you may also try a much quicker approach to kill these 2 guys. Simply, when the level starts, approach the patrolling guy as described above, but instead of twisting his neck, kill him with the knife (which will save you a lot of time). Once he?s dead, IMMEDIATELY get close to the other guy (using the WALK, then CROUCH-WALK mode) and kill him with a headshot from your silencer (or by twisting his neck/stabbing him). If you didn?t waste any time killing the patrolling guy, you should have plenty of time to aim perfectly at his head before he moves towards the elevator. The camera may beep a couple of times, but it won?t spot the corpse at all! Note: If you?re REALLY (but I mean REALLY!) quick, you can even kill BOTH guys by twisting their necks using this same approach. The key is to hold down the forward + strafe keys when killing the patrolling guy (I mean during that cutscene) and then perform the RUN + WALK + CROUCH-WALK combination to get as quick to the other guy as possible (though it's also possible to do it via WALK + CROUCH-WALK).
There are still 7 enemies left for you to kill in this upper part of the mines (5 in the nearby room + another 2 behind the truck), but since killing them may sometimes alert the enemies in the lower part of the mines, you?ll do it later.
Now it?s time to descend to the lower part of the mines. Of course, you can use the elevator, but since there?s a guy standing right underneath it (+ another one patrolling nearby), it?s better to use the ventilation shaft. You can go through it using even the RUN mode, and still, no one will hear you. The 5 guys inside the nearby room may beep something, but they wouldn?t hear your steps long enough to be alerted, so just run all the way through that shaft. When nearing its end, switch to WALK mode, and then carefully get out of it, lying in CRAWL mode. The 1st objective is now accomplished.
THE 2 GUARDS PATROLLING THE RAILWAY
Now notice that small terrain depression just in front of the shaft. If you position yourself properly in this depression, the 2 guys patrolling the railway won?t see you at all (see this pic). As you can see, these 2 guys always stop at each end of their patrolling route for a while, so just wait till they?re walking away, and then carefully crawl towards the left side of the nearby shack (see this pic). Just be careful, because one of these guys (from now on, I will call him ?blonde guy?, since he has blonde hair) may occasionally turn back when walking away, so just wait till he?s in a safe distance, and then make your move! Just remain hugged to the rocks (and in crawl mode, of course) when getting towards that shack, else the guy standing near the elevator may notice you.
Now carefully approach the front left corner of the shack (hugged to the wall). Both guards should now be on their way back, so just wait a bit, and then use the peaking/thermal vision to be assured they?re both BEHIND the shack (in which case they won?t spot you), and then quickly open the doors and hide inside.
Again, you can have a lot of fun killing those 2 guys :) The trick is to kill them when they?re on their way TOWARDS the railway tunnel. The shack you?re in will provide you a perfect position for commencing your approach, so the rest is pretty simple? First, switch to CROUCH-WALK mode, then equip your knife, and position yourself hugged to the doorcase (while being still INSIDE the shack). Use the peaking to know when the guys once again start walking towards the railway tunnel, and AS SOON as the blonde guy is around 1-2 m away from this nearby shelf, start approaching him diagonally, using strafe keys. This guy is a bit of a problem, because his patrolling route is not always the same. Sometimes, he just goes straightforward (see this pic), but sometimes, his patrolling route tends to have a zig-zag pattern, making it harder for you to leave the shack without being noticed (see this pic). In that case, you?ll basically have to wait till he passes that aforementioned shelf to be assured you can leave the shack without any worries, since in most of the cases he won?t do any ?unnecessary? zig-zags from there on. Another important thing is to WATCH THE GUY?S HEAD. That is, if he?s turned to the right (i.e. away from you), there?s a big possibility that he won?t spot you (in which case you can leave the shack MUCH sooner), but if he?s turned to the left (i.e. towards you), you?ll have to wait a bit longer to start your approach?