For this to unlock you must obtain the following achievements in one play through:
Alyosha, Damir and Duke.
This will unlock at the end of your play through - at the start of the credits.
Each of these achievements have specific requirements, however they can be summed up by having good Karma at the end of the game.
Also, killing any surrendering humans will result in bad Kama as well, so don’t do that.