There are multiple endings in Dishonored, one of which is considered the good ending.
Without spoiling much, the good ending essentially means stopping the plague and saving the city.
Getting the good ending in Dishonored basically just requires you to beat the game with a low chaos score. This will take a little bit more work than just plowing through the game and killing all of your enemies. You can still kill people, but you’ll only really want to do it if you are in a pinch, or you’re bored and want to mix it up a bit.
There are other benefits of having a low chaos score as well though. Rat swarms don’t appear nearly as much, and neither do Weepers (those sick people that like to roam around puking all over the place).
To keep a low chaos rating, you just need to try to keep the kill count to around 20% or less. Personally I would stay well under 20% just to be on the safe side.
Here are some tips to help you keep a low chaos rating:
Got a low chaos rating at the end? Congrats.. you’re the hero and you saved the world from the plague. Now play through again and KILL THEM ALL!!