Alan Bligh and John French are a double act, writing team who designed Dark Heresy's Insanity and Corruption rules, as well as producing the guidelines for Dark Pacts. Here, Alan and John describe the process they went through.

Alan Bligh and John French: The 41st Millennium, to misquote a popular saying, is a good place to have an adventure but you wouldn't want to live there. It a place of grim struggle and unimaginably savage conflict, a place where living nightmares come crawling out of the darkness to feast. It is also a place of far more subtle but no less dangerous perils, where ambition, intrigues and temptation all hold their own terrible risks, and where the forbidden is forbidden not just because the powers-that-be say so, but because some knowledge is so dangerous it can not only burn your soul, but perhaps spell the death of millions if unleashed.

Dark Heresy is a game centred at its heart around those who fight the shadow wars against all the terrible dangers that threaten to overwhelm mankind from without and within. We call these 'lucky' few, be they sanctioned psykers or underhive scum, the Imperium's best or just caught in the wrong place at the wrong time, acolytes - a catch all term for the myriad servants and agents of the Inquisition. One of our challenges was to come up with a unified framework by which all the horrors of the dark and murderous cosmos, both insidious and cataclysmic could work their spiritual and mental ills on unfortunate acolytes.

A Number of Very Bad Things

In the milieu of Dark Heresy there are many truths and horrors that can shatter people's minds and contact with them can (and does) change people in ways that can be horrifically obvious or insidiously subtle. In designing Dark Heresy we were very keen to reflect the very bad things that the universe could do to a fragile human mind, coming up with three broad categories:

* The affect on the mind of confronting horrors and terrible truths.
* The corrupting effects of contact with Chaos and the warp.
* The fall of a character through voluntary damnation.

Together these three categories make up some of the unique flavour of playing Dark Heresy and the effects they could produce in characters were some of the features we were most exited about getting to grips with. Our answer was a new threefold mechanic linking together Fear, Insanity and Corruption. One of the ideas we were most keen on was that these three aspects would be inextricably linked and progressive, in fact almost 'telescopic' in effect. For example, a frightening event or encounter would have immediate consequences in the 'here and now' of the game, but, after the encounter was over, it might in turn lead to lasting psychological trauma and perhaps even permanent erosion of the character's mind. Depending on the nature of the experience, the Acolyte might become tainted with the corrupting power of the warp. The system's structure we have used has the effect that shock is relatively common, trauma moderately so and long term disorders rarer.

Fear, Insanity and Corruption in Action: The Man with No Face

Mesmer is an acolyte, part of a team investigating a series of murders on Baraspine where cult activity is suspected. Mesmer is helping to search a reputedly haunted and abandoned hab-stack at the edge of the underhive. He enters a wrecked hab to find a man in tattered preacher's robes standing in the corner with his back to him. Mesmer challenges the preacher, who then turns to reveal a ragged wound where his face should be, and holds out blood-drenched hands as the sounds of ghostly crackling flames fill the air…

In game terms, this situation calls for a Fear Test. Mesmer's player fails the Test and rolls for the effects of Shock, with a modifier to his roll imposed by the severity of his failure. This results in Mesmer immediately collapsing from shock and an amount of inflicted 'mental damage' in the form of Insanity Points. Because the Insanity was brought about by a warp entity (the faceless preacher is in fact an Astral Spectre), Mesmer receives a number of Corruption Points as well. Depending on Mesmer's relative level of Insanity, he may fall into a traumatised state that impairs him for hours or even days afterward, and might even gain a long term disorder appropriate to his experiences — such as vivid nightmares or a profound phobia of pictures showing people turned away from him, fearing when he looks away, they will turn to watch him with their empty faces.

His fellow Acolytes find Mesmer seconds later unconscious on the floor of the hab, muttering and shivering with unaccountable bloody hand prints on his face. The team's sanctioned Psyker determines with her warp senses that something has passed this way moments before. Clearly more is going on in Baraspine's slums than the activities of some petty cult…

Acolytes have two 'hidden' characteristics right from the start that track their slide into madness and warp taint respectively: Insanity Points and Corruption Points. The number of Insanity and Corruption Points that a character has determines what (if any) other effects also come to bear upon the character, as well as helping to determine their chance of developing permanent disorders, malignancies of the soul or even spontaneous mutations. It is of course possible to recover to some degree from mental trauma given the opportunity, however warp taint is a different matter and having gone so far into shadow, the temptation for some will be to embrace the darkness…

Importantly we wanted the effects of Insanity and Corruption to be characterful and profound, but not overwhelming or overly mechanistic. Our aim with this system was to provide GMs with a valuable and flexible tool set. A bespoke system easily modified to suit the flavour of your games and broken down into convenient blocks, which can be used (or not) as you wish, placing control in the hands the GM (and to some degree the players too) over what occurs to the acolyte's mind and soul as a result of the horrors of Dark Heresy .

Damnation the New Old Fashioned Way

One set of options we came up with that you'll find in Dark Heresy , (which I'm sure will surprise some) allows for acolytes to enter into their own pacts with the Ruinous Powers and other agencies of darkness. These pacts are not, I hasten to add, 'marks of chaos' or fealty in the usual sense, but rather secret Faustian bargains, achieving some heartfelt end such as vengeance, forbidden knowledge or even as an attempt to gain some measure of control over the inexorable corruption of their very souls. Dark Pacts represent another optional layer of the game, an added realm of high-stakes opportunity and a huge risk for your characters; a roller-coaster ride with an inevitably bleak outcome, but guaranteeing a great adventure along the way!

By the Quality of their Enemies will you Know them

One of the other sections of the design of Dark Heresy in which we were very heavily involved in was the Aliens, Heretics and Antagonists chapter, which also of course was inextricably linked to the Fear, Insanity and Corruption system. This chapter is intended principally to provide budding Dark Heresy GMs with a plethora of useful Non Player Characters, creatures and entities from beyond for use in their games. The sections entries are closely linked to the worlds and encounters common within Dark Heresy's Calixis Sector (rather than offering a somewhat clunky and less useful 'A' is for aardvark, 'T' is for Tau approach), and should offer a wealth of options. There are literally dozens of entries here featuring everything from the Astropath to the Heretek, and the Scribe to Servitor Drone by way of potential antagonists. While the aliens include a variety hazardous (or useful) flora and fauna ranging from the familiar such as the Grox or the Brain Leaf, to singular new creatures such as Dusk's deadly Nightwing. The last section in this chapter deals with the denizens of the warp, ranging from Unclean Spirits to the savage Charnel Daemon, and we couldn't resist fitting in a couple of the warp's most terrible creations in the shape of horrific and malevolent Daemonhosts and the appallingly dangerous Psychneuein. While the entries in this section are by no means exhaustive of the huge range of possibilities inherent in the Warhammer 40,000 background, it's our hope that with these examples and the full range of creature Traits this chapter provides, that GMs will have all they need to create their own NPCs, xenos and warp entities and be able to excise their own creativity to the full.

Well that wraps up these brief notes from us detailing our efforts to make sure Dark Heresy lived up to its title and we hope that you enjoy the dark delights we have laid out for you.