Players have the option to finish the game without killing any other character, though most are unlikely to achieve this, given its difficulty. When they do engage in combat, it's bloody, with severed limbs and bloody stains.
Players use pistols, crossbows, swords, grenades, and other weapons to kill human enemies, those kills are sometimes accompanied by slow-motion effects and gurgling sounds.
Corpses are often devoured by packs of plague-infested rats and there are corpses strewn around this plague-ridden town.
Using stealth allows the player to sneak up on enemies unaware, with sight of a sword plunging into the necks of the victims with accompanying blood sprays, seen from the first-person perspective.
A 'Kill Cam' is also engaged on occasion with more of a focus on the finishing blow, which may include the decapitation of the victim.
When incendiary bolts are used as weapons against enemies, the victims scream and are immolated, while grenades are able to explode enemies into bloody chunks of torsos and limbs.
It is also possible to kill innocent characters, including women.
During one interactive sequence, Corvo brands a restrained man's cheek with a hot iron; in another, players use electric shocks to interrogate a blindfolded man in a chair.
Corvo can possess creatures to sneak past guards and traps, or can even turn traps against his enemies.
If the player does engage in combat and kills anyone, the 1st person perspective of the game gives a brutal close up of the death. Also, if the player chooses, Corvo can kill an enemy and have the enemys body dissolve into ashes. At times, significant amounts of blood will issue forth during kills and limbs can be severed.
Humans are the primary targets in the game, but the level of violence is going to differ depending on the player. The player is not required to actually kill anyone to complete the game. As implausible as it sounds the game encourages players to take the "non-lethal path" and complete the game without killing their targets.
It should be noted that the enemies in this game are not push-overs, and killing them can be somewhat difficult to do, given that they put up a great fight towards the player. It can also be difficult to beat the game non-lethally, but doing so rewards players with "the best" of two possible endings.
Some environments depict mutilated corpses on the ground or hanging from the ceiling.
Completing the game non-lethally requires a lot of sneaking, cleanup and preparation, but it's much less violent than the lethal path.
Players who take the non-lethal path to complete the game will strangle hundreds of enemies to unconsciousness or shoot them with "sleep darts". It is a bit violent, but no one actually dies as a result.
After a target is rendered unconscious, players will have to store the bodies in hidden locations to remain undetected. It seems more comical than violent.
Players can slash, stab, or shoot enemies with swords, pistols, and crossbows, which causes blood to splatter on the environment and screen. However, some of the blood is difficult to see due to the overall chaos of the action; pistols cause smoke and flash effects that obscure the blood. Limbs can be cut off and thrown at other near by enemies.
Whenever an explosive is used, it sends bits of shrapnel around which instantly kills enemies and causes some blood splatter or gore. It is often difficult to see however, due to the cloud of dust that is left behind.
The violence level will spike when the player uses certain powers to kill their targets. For example, a special type of spell causes a swarm of plague-infected rats to appear and graphically consume the enemy within seconds, all involving blood and gore.
If the player is lucky, they can also execute their targets up-close with a sword. This often results in graphic decapitation or something of similar nature. However, these executions are a lot harder to perform than they sound, because getting close enough in front of an enemy to perform them is nearly impossible to do. This prevents almost all players from seeing these executions.
Parents' note that while this game may seem very violent, the true impact of the violence is lost in the fact that the game rewards players for not killing anyone. I expect that many players will choose the non-lethal path of gameplay, because it's less difficult and leads to "the best ending".