Sniper: Ghost Warrior 2
37 Achievements
20-25h
Psst, Don't Look Behind You
Kill 15 enemies with a stealth kill
26.0%
How to unlock the Psst, Don't Look Behind You achievement in Sniper: Ghost Warrior 2 - Definitive Guide
FuneralTrist
TrueAchievements
TrueAchievements
I thought I'd add that, on medium difficulty, I was able to sprint right up behind him and he never heard me. I don't know if that would still work on hard, though. However, you do have to come to a complete stop to perform a stealth kill and not a simple melee kill. Hitting
in a sprint probably doesn't count because he just does a normal melee attack and not the whole animation.
XniresistX
At any time in the game you can kill with your knife using 
. For a knife kill to count as a stealth kill, however, you need to be behind the enemy and wait for a text indication at the bottom of the screen to pop up. If done correctly, an animation of you stabbing the enemy in numerous ways will happen, if not then it didn’t count.
To check and see how many stealth kills you have performed, from the main menu choose extras, choose personal stats, and then choose general. It will be displayed on the right under a few other statistics. This trophy is cumulative across all playthroughs and mission selections.
MeonOner, Nevander
This will come with natural progression. To perform a stealth kill, you will need to get close behind the enemy and press down on the 
. I recommend performing stealth kills when there are one or two enemies around.
To check your progress and kills, from the main menu select extras and personal stats.