The Darkness Falls achievement says it's granted when you switch the map from day to night. I noticed that at some points in the game, the day-night transition is done automatically (Haunted starts at night, and finishes during the day). Are there enough of these for a player to use only automatic day-night switches to complete the story without having to trigger it manually?
i believe the idea is to manually trigger the feature.
So, like me, if you have never heard of it and believe in just stabbing qunari in the face, you might never bother to get this.