If you are looking to skulk your way through the mean streets of Karnaca, you will want to make sure to avoid as many guards as possible. In Dishonored 2, much like the original game, there are levels of alertness that will signal when a guard has seen you, is actively looking for you, or has been fully alerted to your presence. This is important as several achievements are tied to having no one alerted during either a single mission or the entire game.
When an enemy spots you, a white bar will begin to fill up over their head until it goes completely red. If you are just briefly spotted and the white bar only appears for a split second, that means the guard will have barely noticed you. This will normally cause them to stop and stare for a moment, but they will rarely ever investigate. However, if the bar is filled up further they may come looking where you last were, which means you should move away from that spot as quickly as possible.
However, if the bar goes fully red that means they have seen you and are alerted to your presence. This will cause them to hunt you down and attempt to kill you if you do not flee. Killing all of the enemies that have found you will cause the alert level to drop or when they’ve lost sight of you for a fair amount of time. The only ways to stop guards in the red is to either slay them, knock them out, or hide while they patrol for you. If you are quick on your feet and stick to the shadows then this shouldn’t be much of a problem during your journey through Dishonored 2.
Make sure to visit our ever-expanding Dishonored 2 wiki for all your tips, tricks, guides, and trophy/achievement walkthroughs.