To the tastes of many, and for the purposes of many styles of campaign, the 2nd edition of Dark Heresy is a clear improvement over the first. The tuned-up system improvements make combat more balanced, the character generation process yields more capable characters and offers more flexibility, you can viably play an Inquisitor with just the core book, and the Influence stat and the various things it can be used for (including the summoning of high-powered Requisition Characters as backup) really helps to support the idea that the player characters are Inquisitorial agents with institutional power behind them, rather than disposable schlubs thrown out there to make their own way on a “the Inquisitor will disavow all knowledge” basis.
On paper that all looks good… but there’s a particular style to 1st edition Dark Heresy. For all its roughness compared to the rather smoother 2nd edition, there’s an itch that the 1st edition scratches better than everything else. Yes, your characters are about as incompetent as starting WFRP characters due to the system being adapted wholesale from 2nd edition WFRP. Yes, your psyker will very occasionally detonate and wipe the party. Yes, your character progression is about as rigid as you’d expect in a society as fascistically regimented as the Imperium. Yes, the basic assumption seems to be that you are thrown out there to investigate hideous threats to humanity in a universe where humanity itself is pretty hideous with precious little backup, making your party somewhat more competent equivalents of Paranoia Troubleshooters.
The thing is, that’s all awesome. This is a game where you fail a lot unless you do your damnedest to get positive modifiers on your side and where a fair fight is for suckers, and I am down with that because it encourages smarter play than brazenly confronting your foes like this is yet another Hollywoodtastic power fantasy. This is also a game where the unfair laws of chance will sometimes curbstomp you even if you’ve done everything right, and I’m cool with that because most of the extreme failure states are at least everything. I note a lot of 40K fans, particularly but by no means exclusively yankerdoodles, dislike baseline 1st edition Dark Heresy because they don’t think it’s particularly heroic, which just shows that they don’t get the setting – there are no heroes in the 41st Millennium and if you believe they are you’re a chump who like so many others has swallowed the setting’s internal propaganda like it’s actual fact. (There’s a distressing number of 40K fans who believe that the Emperor is actually canonically intended to be infallible, rather than just being claimed to be infallible by the Ecclesiarchy whose very existence makes a mockery of all that he strived for; proof, if ever any were needed, that reading comprehension and critical thinking are just as lacking in geek circles as they are in wider society.)
In terms of setting a template for all Warhammer 40,000 RPGs to follow, Dark Heresy may have bedded in rules which work fine for my beloved Acolytes-as-Troubleshooters approach but which became increasingly inappropriate for other expressions of the setting, but aesthetically it was excellent. I particularly appreciate the diversity and richness of the artwork; it would have been easy to go for a more cleaned-up and homogenised art style (as WFRP2 was doing at the time), but they went for the wilder and more characterful stuff instead, and whilst there are missteps (almost all the illustrations of woman assassins are basically fetish art with sci-fi weapons added, and c’mon folks, I dig that particular set of fetishes as much as anyone but there’s a time and place) but these are well outweighed by the quality work (like all the lovely John Blance pieces). This may seem like a small thing next to the overall game design, but I would say it is crucially important for setting the tone and atmosphere of the game and conveying the fact that when you get deep into the lore the setting is a much more baroque, Byzantine and gothic place than it’s given credit for in the smoother, cleaner artwork sometimes used for it.
Precisely because of the freedom offered by the tabletop RPG format, an RPG will tend to drill down into the nitty-gritty of a setting much more than a wargame or boardgame will; this goes double for investigative RPGs, where the order of the day is specifically about poking overlooked stuff and inquiring just how it’s supposed to work, and where to have a deviation from the norm acting as a clue you need to establish what the norm is in the first place. Dark Heresy may not provide orders of magnitude more depth than the core wargame book in terms of dry facts about the setting, but I’d argue that it was by far the most flavourful Warhammer 40,000 product released since the original Rogue Trader; it’s certainly the game that got me hooked on the universe in a way which no previous media had ever managed to do.
I’d always been a Warhammer fantasy boy growing up, writing off Warhammer 40,000 as an overblown power fantasy (in part, I suspect, because I’m of the generation which would have been passed by by Rogue Trader and first took note of Warhammer 40,000 in the 2nd edition era). I’d been somewhat drawn in by peers playing the wargame in the mid-2000s, but Dark Heresy would mark the point where I became well and truly hooked on the setting, and so it has a place in my affections that no later edition can shake. Perhaps the best thing about the update between editions is that the two games cater to sufficiently different playstyles that there’s room for both in my life, whilst they’re close enough in system terms to drag ideas from one into the other when it would be particularly useful to do so.