I'm sure each and every 40k player/reader has his own mental imagery pertaining to how things look and what the world 'feels' like. Most likely those images are heavily influenced by 40k artwork. Artwork has always been one of Warhammer 40k's fortes, supplying high-quality images in a variety of styles. Whatever the personal style of the creator, such images have always been suitably heroic, gothic/baroque, and grandiose.

For this Dark Heresy game I want to tone the worst excesses a bit. Architecture will still be gothic and Imperial high society will still be suitably baroque. What I'm trying to do away with is the monstrously misshaped pieces of personal equipment, the endless array of bulky and steam-punk-looking machines. So I want to tone it down, not remove it altogether. Less is more and all that.

Example: You meet an Adeptus Mechanicus Magos, who is deep in the mysteries of the Deus Mechanicus (the Machine God). He's still going to be suitably robed and covered with techno-arcane symbols. He's still going to be able to speak to the machine spirits (i.e. interface with anything that has a processor of some sort). He's also going to have various cybernetic and/or bionic upgrades and replacements. He is, however, not going to look like some steam-punk monstrosity, with visible gears, cogs - even exhaust pipes showing. If you get a glimpse of his true nature its going to look ultra-tech, but with a suitable gothic appearance - ornamentation, gilded parts etc.

The same applies to how the world works; everything can't be all bad, corrupt, defunct, etc. Its a dark and dismal world, but it is not all pitch black. People get born, most survive after a fashion into adulthood, get work, match up, get children of their own, die of old age. Their lives may be hard and there is precious little freedom to be had (but who would want that anyway), but death does not lurk around the corner ALL the time, nor is life and endless march of pain, degradation, and abuse (for some it is, but not for all).

Once again this has to do with believability...but more importantly it has to do with contrast. If everything is as dark as it can get, then it gets damn hard for me to make an interesting game. If every Imperial citizen is equally downtrodden and corrupt, then they are all the same and without variety the world gets gray and boring.

Example: Orphanages are a common sight throughout the Empire. Some are undoubtedly nice places to grow up, filled with light and hope. And some are without a doubt pits of terror and despair, where the children prey upon each other and their caretakers heap abuse in every form upon them. But the majority are just...not very nice. The management might be skimming the coffers, leaving the children with little to wear or eat. Or the staff is disinterested and leave it to the children to establish their own pecking order, so that only the strong prosper. This allows me to describe various orphanage settings, rather than have every which one a pit of corruption.

The same goes for threats to humanity, and by extension the Acolytes; there is evil and there is Chaos evil. I don't want a game where every thug is a mutant or chaos-possessed (but no doubt you'll meet more than enough of them). I've already hinted at this with the Ordo Malleus post - and this is definitely Old School - the true nature of Chaos, the existence of the Ruinous Powers, daemons and such, will not be common knowledge even within the Inquisition. Inquisitors and others in the know will be knowledgeable to various degrees, but junior servants are not privy to such knowledge - its simply too dangerous. So you'll definitely see evil and heresy, but it won't always be of the pure Chaos evil kind.