Exorcist

Exorcist is an achievement in Metro 2033.

Overview
This achievement is awarded for completing the levels "Ghosts" and "Anomaly" without dying. This is a relatively easy achievement to earn as all the player needs to do is just do as Khan says, and for Anomaly, on most difficulties the player will not even need to engage in combat, as Khan can usually take care of the nosalises for the player.

Trivia

 * An exorcist is a person who believes that they can drive away evil spirits and ghosts, through prayer or religion. This is most likely a reference to Khan.
 * The icon and name of this achievement could also be a reference to the popular horror film The Exorcist.