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Rivers of London RPG: An Interview

Lynne Hardy of Chaosium was kind enough to tell me more about the upcoming Rivers of London RPG. Based on the best selling-book series by Ben Aaronovitch, Rivers of London combines police procedural with modern urban fantasy. Thanks also to Michael O’Brien for setting up the interview and to Ben Aaronovitch for creating his magical world and sharing it with Chaosium so we can all roleplay in...

Lynne Hardy of Chaosium was kind enough to tell me more about the upcoming Rivers of London RPG. Based on the best selling-book series by Ben Aaronovitch, Rivers of London combines police procedural with modern urban fantasy. Thanks also to Michael O’Brien for setting up the interview and to Ben Aaronovitch for creating his magical world and sharing it with Chaosium so we can all roleplay in his setting.


Charles Dunwoody (CD): Thanks for talking to me about the Rivers of London RPG. What kinds of adventures can GMs and players expect to run in this setting?
Lynne Hardy (LAH):
Entertaining ones, hopefully! We’re designing the rules so that they’ll help GMs and players recreate the tone and atmosphere of Ben’s novels and short stories, so that their adventures feel as if they could be taking place in and around Peter and Nightingale’s own cases. So, fun and engaging, with some mystery and danger thrown in for good measure.

CD: What types of characters can players play? Will they all be police or are there other options? Will wizards be rare? Can players play supernatural beings?
We expect that a lot of the game’s players will want to play magic-wielding members of the Met, so of course we’re providing the rules for them to do so. But the police aren’t the only characters in Ben’s books, so players will also have the option of playing non-police associates of the Folly if their game is set in the UK or civilian members of any number of organizations (even FBI agents) if their game is based in the US. As we’re aiming the game at new players, most of the player character options in the core rulebook will be human rather than supernatural beings. We are also working on an advanced rules section that will include the option to play people at the lower end of the demi-monde scale—someone like Zach Palmer, for example. Playing a more powerful member of the demi-monde, like a river or high fae, will be tackled in a separate supplement. One of the many cool things about the Rivers of London books is that anyone can do magic if they know how, and that’s something we’ll be sticking with. And, as readers of the books know, magic is coming back into the world, so practitioners aren’t as rare as they were once thought to be.

CD: The Rivers of London RPG runs on Basic Roleplaying (BRP), a d100 system that powers RuneQuest and Call of Cthulhu. How will Newtonian magic and the powers wielded by the rivers and other supernatural beings be translated into BRP?
Carefully! Paul Fricker, the co-designer of Call of Cthulhu 7th Edition, is our lead designer, and he and I have been working in consultation with Ben on the sorts of spells characters will have access to. As Peter often ends up chucking spells around in the middle of a fight, we’re also going to make sure that magic and combat work seamlessly together. So, while the system is BRP-based, it has its own little nuances so that it best supports storytelling in the Rivers of London universe. As to the rivers and the fae, we’ll be looking at them and their magic more comprehensively in a later supplement, although we will be providing enough information in this book for GMs to use them as NPCs in their own scenarios.

CD: Does the Rivers of London RPG introduce any other new rules or innovations to the BRP system?
As I mentioned earlier, we’re aiming the game at new players and GMs, people who may be coming to gaming through their love and enjoyment of Ben’s books and are curious to see what this roleplaying thing is all about. Mostly what we’re doing with the rules is streamlining them to make them as straightforward and intuitive as possible, both to speed up play and to make them more accessible for newcomers. We’re in the early stages of playtesting at the moment, so certain rules may change depending on how well they work in practice. One thing that I’m pretty certain will stay is that we’ve made the Luck spending rules part of the core game – in Call of Cthulhu 7th edition, while recommended, they’re only optional.


CD: Rivers of London the book series has connections not just to present day powers but also to ghosts and past events. Will flashbacks and experiencing the past be part of the RPG experience?
They may well be! We are toying with ideas for future supplements that would address this, but that’s a little way down the line just yet. And, of course, we’ll be providing advice for GMs on how to handle such things if they want to include them in their own games.

CD: Will a map of London, its rivers, and locations from the novels be included or will getting around and under the city be handled another way?
Here at Chaosium, we like our maps and we have access to some very talented cartographers. As the game’s default setting is London, it would be remiss of us not to have a map of London with the rivers and key areas on it. There’s also going to be a plan of the Folly, designed by Ben (with suitable unmarked spaces to avoid any spoilers for upcoming novels, of course…)

CD: What is your favorite bit of design in the Rivers of London RPG?
As the rules are still evolving, that’s a tricky one. Right now, I’d have to say the streamlined character creation and the Luck spending rules. Character creation is fast so you can get playing as quickly as possible, and Luck spending was always one of my favorite innovations from Call of Cthulhu 7th edition.

CD: Is additional support for the Rivers of London RPG planned and can you share any details?
Ben and I have chatted about potential future supplements—it’s certainly something we’re keen to do and we have quite a few ideas about what those would be, one of which I’ve already mentioned. Whether we do or not will very much depend on how popular the game is.

CD: Many readers of EN World are D&D and Pathfinder players. What would you say if they asked why should they should try the Rivers of London RPG?
LAH: D&D 5e
and Pathfinder are very good at what they do, but they don’t do everything. Different types of storytelling work best when the rules help support and communicate their particular style, tone, and atmosphere effectively. So, if you like the Rivers of London books and fancy trying out a fast, simple to learn system that supports urban fantasy stories in Ben’s unique style, then you should give us a look.

CD: When and where will the Rivers of London RPG be available?
I never like mentioning release dates at this stage in a project as you never know what bumps you might hit along the way. If all goes well, I’m hoping it will be ready for late summer 2021. When it is released, we’ll follow Chaosium’s usual strategy of PDF first, followed by the printed book a few months later. And, of course, it will be available from game stores once in physical form.

CD: Thank you for discussing the Rivers of London RPG with me. Any final comments you’d like to share with the readers of EN World?
We’ve assembled a great team of designers and writers from a host of gaming backgrounds. Paul Fricker and Gavin Inglis I’ve worked with before; Adam Gauntlett, Helena Nash, and Lucya Szachnowski have all worked with Chaosium in the past, though this is my first outing with them; and I’ve known Keris McDonald and Lloyd Gyan for years and was keen to rope them into the Chaosium fold as well! The official announcement about the writers, with more details on them and their resumes, can be found at: Chaosium's website and I’m really excited for everyone to see what we’ve been working on. So, watch this space! Hopefully we’ll have more news for you very soon.

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Charles Dunwoody

Charles Dunwoody


Fish Priest
Mythras is a different animal. It’s roots lie in Mongoose’ RuneQuest II, a formerly licensed product which deliberately broke with some RQ2/RQ3 traditions; while it certainly has BRP in its DNA, its takes on combat mechanics for example are far removed from the old-school approach on BRP that RuneQuest: Roleplaying in Glorantha is, or the modern approach Call of Cthulhu 7th ed. does.

Mythras' roots lie in RQ2 and all later editions of RQ and BRP. When it first released as the latest edition of RuneQuest it was called "RuneQuest 6", as such it was the the first time RuneQuest got a full re-write from the ground up since RQ2 itself 30 years earlier. The first version of Mongoose RQ was written by entirely different authors than Mongoose RQII, and when those authors left Mongoose, RQ6 was written from scratch looking back at all previous editions, not just the preceding MRQII.

It's simply not true that the combat mechanics are "far removed" from BRP or older RQ editions. What is new is what was added - primarily the use of Special Effects, which were initially based on the "Special Success" attacks of Impale et. al from older RQ, but significantly expanded. Special effects are the big change which fans of Mythras are (obviously) keen on compared to the older combat system, but many other aspects are the same or very similar to BRP/RQ - the use of skills in combat, the attack and parry convention, hit locations and armour and hp per location. Some elements of combat and skills have been refined or condensed - combat skills in Mythras are not detailed per weapon attack and parry but grouped into one or more combat styles which group weapons together into a way of fighting.

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It always amuses me when I see BRP labelled as "crunchy" when the same people don't bat an eyelid over d&d, WFRP and Pathfinder without any comment about how labyrinthine those rules can be. When BRP is described as crunchy or complex it's simply due to lack of familiarity - d20 systems are familiar, BRP generally isn't, so the reaction is frequently "it's too crunchy". At the same Call of Cthulhu is the second most popular RPG after d&d5e on Roll20 (Roll20 Blog) I wonder if the system is such a disaster, why is it the number 2 played?

BRP can be as diverse as d&d, it's not a unified system. Dungeon Crawl Classics and d&d5e are both d&d but still quite different. Call of Cthulhu is by far the most popular BRP game, but it's not the only version currently published and supported. You would be hard-pressed to see M-Space described as 'crunchy' and yet it's directly based on Mythras, using Mythras Imperative as a base system. Mythras itself is detailed but is also pretty easy to dial back, which is exactly the approach M-Space takes. Most of the detail and complexity is in the combat system, outside of that it's extremely easy to understand and straightforward to play. Mythras has 5 magic systems but how many you use depends on your campaign setting, in the official supplement Mythic Britain, only animism and theism are used (for Druidism and Christianity), conversely Monster Island expands sorcery significantly adding spells, sorcery colleges and gifts, details a number of cults which use Theism, and details a society of animist tribes. What you use depends on the specifics of your campaign.

Some version of BRP for Rivers of London sounds like a good bet, I know Ben Aaronovitch is a long-time fan of Chaosium games, including Pendragon, Elric and Call of Cthulhu.

I did an interview with Ben and he talks about his RPG background (will be posted on EN World). He does indeed love Chaosium and Call of Cthulhu.


It's simply not true that the combat mechanics are "far removed" from BRP or older RQ editions.
Back when I first got my hands on the RQ6 rule book, “far removed” was my impression exactly (coming from RQ3, which had been my go-to, setting-agnostic fantasy roleplaying system I used for worldbuilding and playing for the better part of a decade). Some examples:
  • No trace of strike ranks whatsoever, the impact of weapon length gone, in their stead a characteristic-dependent action economy with heavy ramifications (getting only one or 3 actions per round is a huge difference)
  • But now there’s a damage reduction system based on differential weapon sizes
  • A special effects system based on random differences of success levels in place of preconceived statements of intent and maneuvering.
  • No more global hit points
Pretty hefty changes, which changes the look and feel of combat—in the eyes of some completely, all other things being equal. But that wasn’t the point.

The point is that when saying that Mythras, or Lyonesse in the example above, is “crunchy”, it’s hardly justifiable to think exactly the same way about BRP, which is a moving target depending on the set of (optional) rules involved. They do differ in some, but very substantial ways.

Not that I think of Mythras as being crunchy. Or it being crunchier as, say, the current implementation of RQG. There’s Mythras Imperative, which is sort of a sweet spot.


Fish Priest
  • No trace of strike ranks whatsoever, the impact of weapon length gone, in their stead a characteristic-dependent action economy with heavy ramifications (getting only one or 3 actions per round is a huge difference)
  • But now there’s a damage reduction system based on differential weapon sizes
  • A special effects system based on random differences of success levels in place of preconceived statements of intent and maneuvering.
  • No more global hit points

Weapon length is very much present in Mythras, in the form of weapon Reach. Initiative replaces strike rank, it just doesn't use weapon length since Reach covers it. Action points and the cycle/round structure might seem like big change, but effectively there's not much difference if you default to 2. Weapon reach is more consequential in Mythras if you're using the Reach rules, compared to RQ2/3 since a long-weapon defender is able to keep a shorter weapon adversary at bay.

The 'damage reduction system' you're referencing is used when parrying, it's simply a less crunchy replacement for working out attacks Vs parries, instead of matching damage Vs ap/hp in RQ2/3, Mythras uses weapon Vs weapon size, including shields which by their nature are unusually large for one-handed weapons. This makes shields a good choice for parrying compared to other "normal" weapons.

Special effects are not based on random differences, they are chosen when you achieve a level of success Vs an opponent. They expand effects such as impale, slash, crush from RQ2/3 but with more options, not restricted to damage. Unfortunately in RQ2 & 3 combats are usually resolved by HP attrition, which in the long run gets rather laborious. Special effects do change how combat is resolved, I would agree they change BRP combat, but they are a certainly a big innovation and I can't think of any reason to lose them now.

Global hp - yep, it's gone, not having it can make combatants more durable, and it's one less thing to track.

None of it make Mythras a 'different animal' 'far removed' from the rest of BRP, no one would describe CoC7e in that way, and yet it has had as many changes.
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Paragon Lost

Terminally Lost
So looking forward to this next year. :) I've thoroughly enjoyed the books and personally feel that BRP is a great fit for this. Chaosium has really been doing good work in the last few years and I for one am glad.

On the whole BRP/Mythras debate. They're related but different in my opinion. I do feel that Mythras is more crunchy. My ongoing issue with Mythras is that the pdfs/books aren't very readable due to the size of the font and type used. Just yesterday I opened up Mythras to compare it to 7th Edition CoC and the readability difference is amazing, showed it to my wife and asked her opinion and she agreed with me, which isn't all that common. lol Even M-Space which I just snagged the other day is much more readable in comparison to Mythras or their Fantasy book. :/


Fish Priest
I don't disagree the main Mythras rulebook went a bit overboard with the font size reduction, when it was RuneQuest 6 the text size was comfortable, but with the name change the page count was reduced by 200 pages! from 500 to 300. At the time it was for print cost reasons, but in the days of 700 page rulebooks (Zweihander), 500 pages seems comparatively modest. The bigger style RQ6 supplements are still available and use the larger layout style, I have also noticed the more recent books are an easier read, like Lyonesse. Most of my reading is on PDF so I don't notice that much.

It's not that Mythras is more crunchy than BRP, it's that BRP is more variant than might be imagined. "BRP" is not a single system but a collection of rules options from different publications, starting with RQ itself and the BRP white pamphlet. Mythras is more consistent and in some areas less crunchy than say, RuneQuest in Glorantha. Mythras uses opposed rolls instead of the resistance table, it groups weapon skills into one or two Combat Styles which use a single skill, it uses weapon sizes instead of calculating weapon hp attrition, it consolidates a number of related skills into one, so Scan, Spot Hidden and Search skills from RQ2/3/RQG are covered by the single Perception skill in Mythras. So I don't agree that it's by default more complex, or crunchy, in most areas it's actually less so, and it's more consistent. If you look at how Mythras has organised the spirits and the Animism system, the way it treats Creatures and their abilities, it's approach to cults/colleges/organisations/brotherhoods and so on, is a far more consistent and comprehensive treatment than you can find in any other BRP/RQ variant. Even the "latest" version of RQ in Glorantha is more of a patched version of RQ2 with some additions from HQ and RQ3 instead of a revised edition.

The exception for Mythras is with combat which is more detailed than most BRP systems, certainly potentially more complex, but it's also more interesting and more decisive. Older editions of RQ suffered from magic-enhancement bloat and hp-attrition wars which Mythras has strenuously avoided by being careful about stacking rules, you can't produce the abominations you could produce in RQ3 (see the Lunar Coders from 'Strangers in Prax'). Of course Mythras is 'different' but so is every BRP game from each other.

Andrea Rocci

"BRP" and "Fast and simple" cannot be used in the same sentence. I'm still salty after The Design Mechanism ruined Lyonesse RPG with an extremely crunchy Mythras system (BRP derivative). And new BRP-based RuneQuest is almost a meme at this point with 4 pages of mounted combat rules.
The versions you mention are complex, but BRP can be very simple.
This is the BRP core rules: Game Rules (Online SRD) – Basic Roleplaying
An it's very, very simple. Call of Cthulhu (any edition) is also a version of BRP, and it's very simple. From what Lynne Hardy says, I get the impression that Rivers of London will be close to CoC7.
Mythras and Lyonesse are technically NOT BRP, even if they clearly have BRP ancestry. The latest RQ is based on RQ2, which is the (crunchier) ancestor of BRP. Historically, the first BRP booklet was born as a stripped down version of RQ2. An still today, the latest version of RQ has dozens of rules that are not in the latest BRP SRD.
So, it all depends what additional rules they put in there besides the core.


I’m unreasonably excited about this. Chaosium’s Call of Cthulhu was my first tabletop RPG mumble years ago and so I’ll always have a soft spot for them in my heart.

More to the point, about two months before Chaosium announced that they’d landed the rights, I started writing a one-off RoL tabletop to run at a (now postponed) gaming convention. By a sheer coincidence, I’d decided to use BRP for what little rules-smithing I need (I’m a very rules-light GM) just because I figured it would be the easiest system for players to pick up on the fly at a convention.

Because I’m not much of a rules-smith, I heaved a massive sigh of relief when I heard the news from Chaosium. At this point, they’ll be publishing before my local gaming con returns (if it returns, sigh) and that should save me SO many headaches. I’m sure Chaosium’s worst day is going be about ten times better than me at my best. ;)

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