Pacifist

Pacifist is an achievement/trophy in Deus Ex: Human Revolution. It is earned by completing the game without anyone dying by your hand. (Excluding boss fights, which don't count toward this.)

Overview
The aim is to complete the game without killing anyone directly, or someone dying as a result of an action taken by the player. The  only  exception to this is the Boss fights where killing them is permitted while preserving the ability to obtain this achievement.

This achievement starts from the first moment of the game, when Adam Jensen is not yet augmented; killing anyone in the Prologue chapter will lock out this achievement.

Strategy
Obtaining this achievement is not as hard it sounds; even in Hard difficulty it is quite straight forward.