Tomb Raider: Definitive Edition

This is unlocked by pulling enemies off of ledges by shooting them with the rope arrow.

Once you have the rope arrow unlocked, equip your bow. Find enemies that are near ledges. Use left trigger to draw your bow and to fire a rope arrow. If your enemy is close enough to the edge, it will pull them over. Rinse and repeat with four more enemies.

NOTE: This does NOT seem to work for armored enemies. I was only able to get this to work on the basic thugs like the ones at the beginning of the game.

I was able to unlock this after completing the main story, however. I chose the Continue option from the main menu and went looking for unarmored enemies. There are still a lot of enemies in Shanty Town. When I found a lone enemy, I got him to chase me to an edge and I jumped off. Then, turned around and fired a rope arrow.

Tip from Theodoricus Rex:
For everyone having trouble pulling it off (no pun intended): make sure you aim for the head.
I almost never succeeded in rope pulling the enemies of ledges without aiming for their heads.

Here's my guide from the 360 version, if you fully upgrade all your weapons enemies will stop spawning preventing you from unlocking this...

You unlock the rope arrows during the story once you have, you need to find enemies near edges of roofs or cliffs.

Fire the rope arrow and you'll pull them towards the edge and hopefully off.

If they sort of duck and run from it this means they have armor that you'll need to dispatch before you can pull them. To do this just hit them with a single arrow make sure you don't charge it and you'll see the armor get knocked off then just fire a rope as normal.

If you've completed the game and still need this achievement.

Head on over to Shanty town, near where the big gate is between the two areas of the town a few enemies will spawn.
Let them spot you and then run away, climb to a nearby rooftop and they should head on up to a different rooftop and continue firing arrows at you.

Hit them once with an arrow to break their armor (don't hit their heads or hold the shot for too long) then use the rope on them to pull them off the roof.

I only needed 1 guy, if you need 3 or 4 this should work for you.
Want to vote negative, feel free to comment...

This solution contains the two earliest opportunities to get the rope arrow kills needed towards this achievement during your single-player campaign.

As a precaution, once you come across these areas you should save again but on a different save slot. Press the Menu/Start button and go to "Change Save Slot." This way you can try again if you fail as the game autosaves often. If you do fail and it autosaves, you must choose the option "Exit to Main Menu" and press "Continue" on the other file, otherwise, it will overwrite the save file. It's a good idea to save on all three save slots from time to time.

This first area is the same area where you acquire the rope arrow. Which is right after you fail to rescue the first pilot from the down rescue plane. As soon as you get hold of this new weapon there will be 5 enemies right above you. The first two you take out won't count, but the next three will. Try to get all three. Each guy will probably take 2 or 3 rope arrows before they come down.

Kuddlesnot Youtube video "#6 - Tomb Raider 100%: Return to the Village" at 12:00 shows you the location.

This next area has 8 enemies that can be prompted to get near the edge of the cliff. It may be a bit difficult to get all 5 kills here, but it's definitely possible. The difficult part is getting them to follow you to the edge of the cliff and not getting killed in the process. This area is located soon after you receive a call from Sam in which the guards find out that Sam has taken their radio. You will ride down a zip line and crash down into the roof a wooden shelter. There will be 3 guards trying to fix a fuel leak. Run past them to the right and go straight to the edge of a cliff. Take cover behind the wooden barrier and get their attention. To make this a little easier, while there take some shots at them, but don't kill them. Eventually, you will get them to come close enough to the wooden barrier that they will follow you to the edge of the cliff. Once they do, run across the wooden beam to the other cliff where the ammo boxes are. Stand your ground and take out anyone who shows up with your rope arrows as quickly as possible. There will be 5 more enemies coming up to get you once you take these 3 out. You will have to get them to follow you to the edge as well otherwise, they will shoot you from below. Rinse and repeat. Kill a few straight away if needed to make things easier.

Kuddlesnot Youtube video "#8 - Tomb Raider 100%: A Shanty Town Adventure" at 1:50 shows you the location.

Overall Kuddlesnot Tomb Raider videos give great advice in dealing with all the achievements.