I’m here today with a long review of Cortex Prime game system, a big topic that I’m determined to get all into a single post. This is the next iteration of the game system behind Marvel Heroic Roleplaying and the Firefly RPG to name a few. I’m a big fan of those and I’ve been really enjoying trying out Cortex in a variety of ways.
The Cortex Prime Game Handbook promises a lot in its introduction. It was written to be a multi-genre game appropriate for a variety of settings, and a modular game with tools to take in or leave out as you like. Basically, whatever sort of story in whatever sort of style you want to be telling, Cortex wants to be there for you. This is a big claim and the main reason I’ve been doing so much testing before reviewing the game here. How well does it stretch to different genres? Well, not to cut to the end but it does it surprisingly well. Let’s dive and take a detailed look.
The crux of the Cortex system is dice pools of variously-sized dice. You probably roll three dice for most tasks but you might have a lot more and even a few less. However many dice you roll, you’re probably only using a few (this is a similar mechanic to the Sentinel Comic RPG, which owed some of it’s inspiration to Cortex). When you roll you’ll pick two dice to add together for your total, probably your two highest results to get the biggest sum as your total. If you have an effect on the environment or another player (such as in combat or when working to create something) you pick a third die to be your effect die. If you get any results of 1, however, that’s a hitch and generally a setback. Rolling all 1s is a botch and that’s very bad.
There’s a currency of plot points too, shared by both the GM and the players, which you can spend to add an extra d6 to your pool or power special abilities (more on those later). You earn plot points by rolling hitches which allow the GM to create a complication which is adds a die to their pool (which is typically from an NPC’s stats or the situation). The opposite of a complication is an asset which is a good thing for you. You generally want big dice because they have less chance of rolling a hitch; you have a 25% chance of rolling 1 on a d4 but a 12.5% chance on a d8, for instance. There’s also commonly the chance to step up or step down your dice to make them a size bigger or smaller respectively.
That’s generally it! Let’s take a very quick example (the details don’t matter, I’ll get into those below) and imagine a typically-made spy-genre character breaking into a building. They might roll a d10 from a Physical stat, a d6 from their Sneak skill, and a d8 because they’re a Super Sneaky Thief. They get 5, 3, and 4 as their results and the GM (rolling 2d8 as this is “challenging”) gets 6+2 = 8. The thief adds two dice for their total (5+4) and gest a 9 which just succeeds. Simple! Now let’s get complicated…
Test and Contest Mods
The default rules for Cortex are described above: adding two dice for a total and then maybe having an effect die. Sometimes you’re rolling to make something (an item, a trap, a plan) in which case you create an asset of the same size as your effect die (Pistol d6, Pitfall d8, Stratagem d4) which can be used in future rolls. In an opposition (including combat) the winner inflicts their effect die as a complication to the target, giving them Broken Arm d6 or Concussion d8 or something (similar to the statuses in City of Mist). If there’s already a complication you might instead step it up to a maximum of d12. If a complication gets stepped up past d12 then the person, ship, or obstacle is taken out in some way (unconscious, dead, hallucinating, etc).
You can make things higher-rolling with adding all the dice mod to end up with bigger totals. You can also use the no effect die mod to make it simpler or a mod to reroll for effect so that it’s not just a single toss of the dice. You can also use a static difficulty instead of having the GM roll. This first set of mods is not terribly exciting and I’m not sure I’d even recommend any of them, but they are there and now you know about them.
Traits and Mods
Where the flexibility of Cortex and its modular nature really starts coming through is in the character Traits. This catch-all term covers a lot of very different game options which you cherry pick for your particular game in the Cortex system, creating your game’s prime set. These are collections of at least two Traits but potentially up to seven Traits. You need three dice for a good pool so if you have only two Traits in your prime set you need lots of other options around; I recommend having three Traits as a minimum.
The two most common types of Traits in Cortex games are attributes and distinctions. Attributes are the classic “ability scores” of a character and many Cortex games use Mental, Physical, and Social as the three. You could also crib the six abilities from Dungeons & Dragons, make a genre-specific set (the book suggests Courage, Faith, Guile, Reason, and Vigor for a swashbuckling game, for instance), or different narrative forces in your setting (such as balancing between Digital, Chrome, and Flesh in a cyberpunk game). All the attributes default to d8 but you can step one up to d10 by stepping another down to d6 to keep things balanced.
Distinctions are much more personal and are typically core values for the character (they in fact resemble Values from Star Trek Adventures) such as Cult Survivor, Super Sneaky Thief, or Laser-Sword Master. All distinctions are at d8 but you can choose to have them be a detriment to gain a Plot Point and roll d4 instead. This increases your chance of rolling a hitch so it’s for when you can say that the distinction is working against you. Maybe being a Cult Survivor helps you stay tough and focused but sometimes you have panic attacks as the memories flood back. There’s a mod option to skip all this and have distinctions tie to another Trait like skills (see below) but I love these so much I’ve never had the need to try that.
Another common Trait is skills which work like skills in other games. There’s a default list of skills (things like Craft, Influence, Fight, Perform, Sneak, and Shoot) but these can be changed up for a given genre very easily. A high fantasy game might include Arcana, for example, while a game focused on espionage might have Tradecraft and Hack (although the book suggests verbs for skill names). Skills all start at d4 but you get a set of points to step them up (or you can tie these increases to distinctions) to a maximum of d12.
On the other hand, you might want to use the skill pyramid mod to make a balanced set of skills like in Fate. Either way, you can also include specialties which are specific concentrations like Guns or Cyborgs to add a d6 to your pool when the roll has to do with that subject. Something very meta but also highly thematic is having roles as a Trait instead of skills, basically replacing granular skills with types of narrative roles for characters. A game set during WWII, for instance, might have Commander, Engineer, Medic, Sniper, and Soldier as roles; some characters are lone marksmen with high Sniper and low Soldier, while the compassionate combat doctor might have high Medic but low Commander. These roles can also have specialties but you can also have specialties without any skill or role at all.
One of my favorite options for traits is affiliations which are ties to groups, setting forces, or even methods and generally in a set of three. This is an awesome way to tie characters to the setting like having Government, Corporations, and Gangs in a gritty cyberpunk game. Each of these gets d6, d8, or d10 to indicate where you’re connections lie. Marvel Heroic Roleplaying has Solo, Buddy, and Team for affiliations to indicate the dynamics characters were best in rather than organizations, just to show the versatility.
Something that I’ve played around with in a lot of games is relationships. These are connections to people, places, or groups that your character have which can spur them to greatness. If they have Mother d8 then they add that die to their pool for defending their mother, when following their mother’s advice, or even when acting the way their mother taught them. This is also a great way to tie the setting into character stats like with affiliations, though this way you might end up with characters that have no relationship to a group so it depends what you’re going for. There’s also a mod to make this reputations instead which is an excellent option for many stories.
For superhero, supernatural, or just generally super-powered games you might end up with individual powers as a Trait. This is a massive mod that has a lot of sub-options for getting exactly what you want but the most basic form is to have individual powers that are rated with a die. You might have Super Strength d8 and Power Armor d10, for example, or Teleportation d6. You can gather these into power sets using a mod which links them thematically (how Marvel Heroic Roleplaying does it) so that your Super Strength and Power Armor are all from your Exosuit or whatever but your Genius Intelligence is from another set, which helps you mechanically too. Then there are abilities to establish different types of superpowers and then a long list of abilities and powers to get you started.
Powers and abilities are probably the biggest use of SFX in the game but these can also be attached to anything from distinctions to roles and even relationships. These are rule breaking/adjusting abilities that let you use a fun trick for some initial conditions or cost. Very often this is spending a plot point for an extra die or to create an asset immediately but sometimes it gets very interesting. For instance, you might be able to “split” a die by stepping it down and adding a new one (such as turning a d8 into two d6s) but only against a group, showing your ability to handle crowds of low-level minions. One of my favorite options is stepping down one trait to step up another, momentarily being distracted to punch harder or becoming animalistic to gain enhanced senses.
Lastly, using values is a way to underscore the themes of the setting in your game mechanics by listing specific concepts that every character in the setting falls between, with varying die ratings. I talked about a similar use of values when I reviewed the new Dune RPG and like that game the most straightforward application is with moral values. You might have values of Duty and Justice for a superhero setting or a darker setting with values based on the Seven Deadly Sins. I like the idea of a knightly code for an Arthurian setting with each point being a value, then you have knights who value Chastity more than Questing or vice versa. It takes a setting where everyone has very similar motivations and makes it extremely messy.
One additional trait, resources, is a game option to have shared, external options that the characters can use. There’s also signature assets for situations where a specific weapon, animal, or reputation just doesn’t fit into another category. You can build characters piecemeal, using premade talents, of through an organic pathways system that builds the world along with the characters. There are so many options that it can be a bit confusing but how do they all fit together?
Choosing a Prime Set
The book provides some readymade prime set for different genres. All of them have distinctions for making your character individual (it’s mechanically possible to drop distinctions but I don’t think it’s something you’re starting with) and the Cortex Prime Game Handbook provides the other two. For a heist action story, for example, you have attributes and also the roles you fill on the team (this is how the Cortex-powered Leverage RPG was). For a romantic fantasy story (something like Blue Rose or The Princess Bride) you can instead pick skills and relationships.
The starting point here is straightforward by necessity but there’s a ton of potential in this and a brainstorm on something specific might help. Adapting something like Werewolf: The Apocalypse could have affiliations based on the Renown concepts of Glory, Honor, and Wisdom to bring those into each and every scene, or you’d rather have Tribe ties as affiliations for a very political game. Gifts are handled by SFX and they might be determined by distinctions or you might have a magic-heavy game with powers associated with different types of magic and SFX representing individual Gifts. You might have specific skills like in the original WtA or you might favor roles within the pack, focusing either on individuals or the group in your mechanics. Whether or not you have skills, specialties could be a way for individuals to stand out or maybe this is where the Tribe influence comes in with Black Furies and Glasswalkers having similar Traits but very distinct specializations. And what about the pack totem? Is that a resource, a relationship, or maybe a power? All of these choices turn a known quantity (the world of WtA) into a specific expression on a theme for the type of story you want to tell. Definitely modular.
GMCs and the Doom Pool
The last bit of this (very, very) long review is about the GM side. Cortex refers to non-players characters as GMCs (Game Master characters) and they can be a wide variety of complexity levels. At a basic level, GMCs are just dice pools and sometimes SFX tricks to keep it interesting. The rest is story elements that can help you with coming up with complications as a result of a bad roll. Let’s take a look at each of the types of GMCs in the book and consider a staple 80s action movie scene: a group of wrongly-accused protagonists trying to get away from the cops by running through a crowded mall.
The most basic GMCs are termed minor GMCs which are typically three short Traits and a rating, very thin mechanics but named characters who can be remembered. In the example above, the pair of recurring police officers who keep just missing our PCs might have Uniformed Officer d8, Unprepared d4, and Radio Coordination d6. When the GM rolls for something at involves these minor GMCs they can choose one of these Traits to add to their pool and increase their options. For characters that are a little heavier plot-wise you can make major GMCs which are pretty much made like player characters. They are the big villains and recurring threats, such as the police chief leading the search for the PCs or the criminal who framed them. Light major GMCs have die ratings a step below the PCs, medium major GMCs are about on par with the PCs, and heavy majorGMCs are a little more powerful than the PCs and could be a big threat. You can pick what weight the GMC has on the story by choosing their level.
Beyond these you can have unnamed extras who are just single dice (Mall Bystander d6 or Security Guard d8). They don’t have names or any really weight on the story, they pop in to be included in people’s dice pools and then are left behind as the scene and story move on. For that matter, locations can be GMCs as well as a set of three distinctions that represent qualities or opportunities there. The mall our PCs are running through might have Fountains d8, Crowds of Shoppers d8, and Busy Food Court d8. The PCs or cops might use the crowd as an advantage to block someone’s movement or they might earn a plot point by using it as a challenge to themselves and rolling a d4. It might even have an SFX like being able to spend a plot point to automatically make a Hidden asset.
Continuing to more complex options, you can create mobs as groups of GMCs who are extras but have larger dice options when they work as a group. Maybe the two named minor GMC police officers above have a squad of beat cops with them who have some Traits and a large pool of d6s to represent their collective efforts. You can use these mob rules for very important GMC bosses who can handle a whole group of PCs on their own like big kaijus or just capable combatants. In our action movie example, maybe there’s a highly skilled hitman after the PCs who can act as a boss. Lastly, you can play factions and orgs as their own characters with dice pool to make moves on their own. This is great for having big groups acting in the larger setting and also for when the PCs are squaring off against an organization and you want to keep it us-versus-them. In the action movie, the criminal cartel who is framing the PCs could be a collection of different GMCs, a faction unto itself that can make life hard for the heroes, or both depending on the scene.
An optional mod for GMs is the Doom Pool, a changing pool of dice that gets bigger and more serious as the situation changes. This is the GM system for Marvel Heroic Roleplaying so if you’ve played that you already know it. Essentially, while the players still use the plot points, the GM steps and steps down a pool of dice that is a default environmental collection. This is better for games that are not as cinematic and instead have an increasingly bad world that is working against the characters like horror, disaster, or farcical stories.
And that’s the Cortex system! It’s worth pointing out that I’ve really discussed a little less than half the book here, there are tons of guidelines and resources as well. Notably, there’s a buffet of genre ideas to mix and match and create a setting. There are also three premade settings with established and details prime sets: Eidolon Alpha (a fantasy heroic setting based on classical Greece), Hammerheads (an elite group of emergency responders and the relationships back home), and Trace 2.0 (a police and legal investigative setting with some near future tech).
I started saying that the game had an ambitious goal, supporting any genre and a wide range of storytelling and play styles. After playing around with this for a while and trying different options, I think that Cortex Prime actually meets these expectations pretty well! The different mods and options take the central dice mechanic (the roll-and-keep dice pool with different dice sizes) and translates that into all sorts of conflict from violence and physical challenges to emotional or mental tangles. It really covers a ton of ground but it’s not ready right out of the box for this.
The system is laid out clearly enough but the designers have opted less for modules on specific genres in favor of modules for different game mechanics. When you’re designing a gothic detective series you have to decide if you want to have relationships or affiliations or skills… and those aren’t labeled as clearly. It takes some time to get used to it but I definitely think that after that initial investment this game is ready for whatever type of game you want to be running.