In this case, something substantial would be feeding on the innocent NPCs that make up Vampyr's world. They won't come back once killed, and you'll have to deal with the fallout. Merchants won't be able to sell you things, parents won't be able to look after their children. In our demo, the developer took out one guy, a loan shark. His child, we were told, would now have to fend for himself. On the flipside, the merchant that he was bouncing off of the kerb for protection money was now happier and didn't have to pay out to the loan shark. End result? He had more money and better items to trade with.
To ease your own conscience, you'll have to pick your targets carefully: each character has a name, a job, relationships, even blood quality. You can investigate all of these to make sure you're making the right choice, or you can feed on whoever you find on the streets with wild abandon - just like in the myths, vampires can't enter a home without being invited. Each time you feed you gain more power, so it's a viable strategy, although kill too many people in a district and it'll collapse under the weight of disease and fear, becoming overrun by a new type of lesser vampire, the scabs. These districts are useless to you, so you should probably feed strategically.
You can go the other way too. It's possible to complete the game without killing a single one of the named NPC's, although Szucs indicates you'll have a much harder time. 'The character will feel the need for blood,
' Szucs said. 'What we want to do is use the combat as a stage for you to unleash your powers. Every time you kill someone and feed - drink their blood - you will get really strong really fast. You can choose from the powers through trees and do your own kind of spec. You feel it immediately. There are a lot of advantages and if you really want to dominate your enemies, you will have to drink blood.
I'm expecting to see a lot of Youtube 'no kill' runs where people try to get through with the bare minimum of blood, but just like the 'onebro' runs on the Souls games, don't expect them to be a lot of fun.
All of these consequences play into the end-game, with each innocent you kill and certain actions earning you damnation points which, among other choices, will affect the ending you get. Dontnod warns us that there won't be any redemption endings, or even endings that are good or bad - you're already the monster and this story can only end in tragedy, but the different endings will go some way to defining the texture of your particular tragedy.
Even though it's quite early in production and the game isn't due to appear until 2017 at this stage, it's hard not to be excited by Vampyr. It strikes me as the sort of game Legacy of Kain would have been now, and there's plenty of fodder now for a mature vampire tale. If they can nail the gameplay side down, this is going to be one of the better RPGs of 2017.