Though there are many third-person action games which give players the option of being a sneaky pacifist as opposed to a murderous psychopath, the Hitman games are of course entirely focused on killing people - and ideally, doing so undetected.
Practically every single mission in the series is centered around Agent 47 breaking into a fortress-like locale and offing an undesirable. Though the targets are almost always said to be "bad" people, does that really justify the player killing them in cold blood?
The finessed, puzzle-like structure of each level helps deflect from criticisms that Hitman is simply another "murder simulator," even if that's really exactly what it is - and damn fun, too.
But that doesn't change the fact that Agent 47 flat-out murders people for money and generally slips away scot-free. If that doesn't make you a dick, what possibly could?