Being bodyguard to an empress and guardian to her young daughter sounds like a pretty cushy gig so long as no traitorous official has her assassinated, kidnaps the daughter and frames the bodyguard for the crime.
Sadly, thats just the situation in which Corvo Attano finds himself in Dishonored. After six months rotting in his cell, Corvo is given the means to escape on the eve of his execution.
In league with a resistance movement opposed to the new leadership installed after the coup detat and granted potent abilities by a supernatural being called the Outsider, Corvo sets about hunting down the conspirators behind the empress death with the aim of freeing the young heiress and overthrowing the usurpers.
He does this, ideally, by not being spotted and killing as few people as possible aside from his targets. The more people Corvo kills, the more chaos is generated in plague-stricken Dunwall, a weird alternate-universe Industrial Age port city whose technology boom is based on refined whale oil. Too much chaos can send the games plot progression down a darker path and affect how some characters treat the erstwhile bodyguard.
Still, if the nonlethal way isnt your thing, you have lots of options to the contrary. Corvo is a skilled fighter, and while he can end up in dire straits if hes outnumbered and surrounded, he has a wide array of gadgets and powers to see him through trouble spots.
He starts with a powerful but noisy pistol, and soon gains more versatile tools: a small crossbow that can fire deadly standard bolts, incendiary bolts or sleep darts, grenades and springloaded blade traps.
Even more interesting are the Outsiders gifts. By spending runes carved into whalebone fragments, Corvo can unlock a variety of powers, with a standard and upgraded version of each, ranging from commanding swarms of plague rats to the ability to teleport instantly from point to point and stop time to attack (or escape) his enemies.
A stealthy, nonlethal style of play limits your bag of tricks considerably some of Corvos powers and many of his gadgets are all but useless if youre trying to keep the body count low.