Enlightened

Enlightened is a hidden achievement in Metro 2033 and regular achievement/hidden trophy in Metro 2033 Redux, that can be obtained at the end of the game.

Overview
This achievement is awarded for sparing the Dark Ones at the end of the game in the non-canonical enlightened ending. To receive this ending, the player must acquire enough positive moral points for Artyom to awaken from his dream sequence in time to stop the missiles from destroying the Dark Ones "city" (nest) at Botanicheskiy Sad. Once he has awoken, a Dark One will tell him, "We want peace." Another will be reaching for the missile guidance system - shoot the device to stop the missiles, saving the Dark Ones. If you do not have any ammo left, you can walk right to the guidance system and press Use to drop it down from the tower.