Metro 2033

This achievement is obtained on the "Front Lines" level.

When you start the level, immediately turn around and kill the two soldiers that are behind you. Then, turn back around and proceed through the tunnel straight ahead - in the direction you were originally going. I did not keep count of the grand total for the level, but there are two, maybe three enemies on the same tracks you are on at the start. Kill those (possible with throwing knives if you need those achievements). Then, go down the stairs on the left, and there are another two or three at the bottom of the stairs, plus a box of goodies to the right of the bottom of the stairs. Go forward and down to the left to the next section (be careful not to fall like I did). There will be a handful of enemies here too. Then, go up the walkway to the left and take care of all the enemies up here. Once you get that area cleaned out, REMEMBER TO KILL THE TWO WOUNDED SOLDIERS ON THE MATTRESSES. You can again use your knives - they won't fight back. Proceed all the way across the top to the Fascist gun placement positions at the other end (you'll have to fight your way through once you start getting close to it). When you start going through the tunnel again, be careful of the room on the right. There are three or four heavily armored enemies in that room. Once you've cleaned that area out, a trolley will come with a driver and a gunner. Try and take both out quickly, although the gunner will be the more difficult of the two to kill. Proceed. You will come to an area on the lower right with a few enemies below (this is where the trolley will stop if you didn't kill the gunner previously) - kill them, but DO NOT kill the three captives sitting on the ground there. The reason you don't want to kill them (yet) will be explained in a second. For now, leave them alone.

Once you've cleared out the area around the captives, continue to the end to the Fascist base at the end - there will be one enemy remaining at the end of the tunnel. Take him out. Open the door on the left, and then the second. This will put you in a large open room with no one in it, but there is a ukelele (?) or something you can play - nice touch. There is also ammunition, etc., right inside the door if you need it. There is also a checkpoint right here. Make sure it kicks in and you save. DO NOT open the third door, as you'll be captured, and that's the end of the level.

Now, go back outside to the three captives. If their "leader" is standing, this means you've killed everyone. Go ahead and talk to him, and you will get the "Rescue Ranger" achievement. Once it pops, immediately quit out of the game. Once you're back to the Main Menu, reload your last checkpoint, which will put you back into the empty room. Now, go back to the three captives. This time, shoot all three of them FROM A DISTANCE - they are defenseless. Once you kill all three of them the "Hedge-Hopper" achievement will pop.

UPDATED: At this point, reload your checkpoint and free them. This gives you a "point" towards the "Enlightened" achievement.