It is only a player's choice what to do with his abilities. The game reacts to your choices - grim atmosphere by itself can be turned even darker by killing people or slightly lighter by not doing so. Gadgets are given by Piero Joplin, Loyalists engineer and by the Outsider, who gives Corvo magical abilities. You can spare the lives of your enemies by knocking them out or making others do the job for you or brutally murder everyone in the city.
The main focus of the game is to give the player a choice. Now it is your duty to return the Empress daughter and restore your name. Being accused of murder and waiting for execution in a cell, Corvo still manages to escape with the help of the Loyalists and their leader Admiral Havelock. All of a sudden, a group of assassins kill the Empress and kidnaps her daughter Emily. You play as Corvo Attano, Empress' bodyguard, a masterful assassin and a combat specialist. It is you who will decide what to do with your enemies.