Dishonored: Death of the Outsider

Finishing a mission without killing anyone is fairly easy to do on the first mission. Save often and if you're ever uncertain about whether you killed someone, you can check the mission stats from the main menu. There are only three major places you need to watch out for:

1. In the first part of the level, you need to avoid and or knock-out three guards. The first is by himself with his back to you (part of the tutorial) and quite easy to remove from play. The next two are just past him down the stairs (a fighting tutorial is here). If you jump the railing and sneak down the grassy area, once the guards separate, you can drop knock-out the first one, then sneak up behind the second to knock-him out as well. Undoubtedly it is possible to bypass all three without knocking any of them out if you want to go that route. You can also use stun bolts if you have them, although it's probably better to save them for later.

2. Once past the guards you'll enter a neutral area and head over to the club. Inside, you'll eventually be directed to head upstairs. The simplest way up there is to climb the shelves in the locker room then up through the hole. Cross to the other side, and look through a keyhole to watch for a woman walking the back hallways. When she's not looking your way (e.g., smoking a cigarette), open the door and knock her out. Head toward the mission marker to find another room with two people, including your targets. You need to take them out without killing them. Stun bolts, hook mines set to non-lethal (a bunch of them are in the room nearby), and sneaking up on at least one of them are all possibilities. Fighting them and doing a non-lethal riposte is possible, although hard to do and not recommended. There are some hounds in a nearby cage...killing them will not void the achievement.

3. Once you have the key you can head back downstairs into the neutral area. Releasing Down will make the area hostile, but he'll automatically take everyone in the room out, leaving you free to work your way to the exit. To avoid the raiding guards, head upstairs (not through the main entrance you came in on, but through the cashiers area), back up to the second floor, then through the bar area and into the private room, where you can escape via a window. Jump down into the lower area to your left to avoid the guards, then sneak back toward the exit the way you came. When you get to the area where you eliminated the first three guards, there may be as many as three more of them around (one may or may not come down the stairs, the other two are almost certainly at the top where the first guard was). You need to take them out without killing them and/or sneak past them.

Once past these last three, you can end the level and should unlock the achievement for not killing anyone on a mission.