Raider is an achievement/trophy for Metro 2033 and Metro 2033 Redux, awarded for stealthily entering the first Nazi occupied room in the level Depot. This can be accomplished by killing the first guard before he gets near the room and alert the others. Although you should do this stealthily, it can also be done with a non-suppressed weapon as long as the player kills the guard quickly. A good indicator if the player is too late or not is that the soldier has not shouted and entered the station.
Bronze Trophy - 15
On the level DEPOT silently kill the first guard and break into the Fascist station unnoticed