One of the basic facets of most action games is that you kill to complete the level or you kill to survive. In some games like Splinter Cell, the objective is to complete the missions while being as stealthy as possible. In Dishonored, the mantra is that you can kill but you don't have to and the developers think this will give more meaning to the occasions in which you do kill.
Speaking in a lengthy interview with Gamasutra, Raf Colantonio and Harvey Smith the creative directors behind Arkane Studios' Dishonored, talked about a number of interesting design topics behind the upcoming first-person hybrid from Bethesda. In regards to the option to kill or to avoid killing NPCs, Colantonio stated that...
Initially, we just did it because we had passion, and we believe that only a very, very small percentage of players would do that. Then it kind of became bigger than we thought as we started to talk about it and to add to the game: you actually can avoid killing people and can finish the game without killing people. Yes, it's true, and it's part of our values. But also the fact that you could not kill them gives more meaning to the times you do; it was a choice between killing or not. Yes, it is important.
I think that's an interesting way to look at it because in most games, like Call of Duty for example, you're mowing down hundreds of no-faced "bad guys" to get to the end of the level. It's rarely about thinking about consequences, characters or outcomes, it's simply "This faceless baddie is in my way, thus my M4 carbine must teach him a lesson by inseminating 5.56 round into his forehead". In Dishonored, Bethesda has more of IO Interactive's Hitman maxim in mind: the game will progress one way or another depending on if you decide to kill everyone or not. It's interesting and definitely a good way forward for a lot of games.
Raf follows up on this exact sentiment, saying...
[Players] feel in an environment which is simulated. As opposed to "this is what we want you to do," it's more like, "Hey, what are you gonna do?" In this case, when [players] do something like killing, and they knew that they could have avoided to kill, they might regret it a little bit. They might feel emotions that they would never feel otherwise.
I'll be honest, those sort of things do play with your emotions quite a bit. X-Com, the original from the early 1990s, definitely hit on these emotions because when doing Terror missions you, the player, were responsible for the safety of civilians. Every civilian killed would knock off your rating and potentially affect the morale of your troops. Being responsible for someone's life in a game is a great way to approach the subject matter in a much more mature fashion than simply racking up body counts to complete objectives. That's not to say that the Dooms and Left 4 Deads aren't fun.
Hopefully Bethesda didn't bite off more than they can chew and the whole game evolves into something both noteworthy and memorable. You can look for Dishonored to release for home consoles and PC this October. Feel free to check out the entire interview with the lads from Arkane Studios regarding Dishonored over at Gamasutra.