Review – John Carter of Mars Roleplaying Game

There has always been a dichotomy between fantasy and science fiction tabletop roleplaying games. The king of fantasy has, of course, almost always been Dungeons & Dragons (and when it wasn’t D&D, it was Pathfinder, part of the D&D family tree) – something that started as a system and a genre, but not a setting (unless you count the recent Guildmaster’s Guide to Ravnica, which uses a setting from Magic: the Gathering). On the science fiction side, there have always been science fiction roleplaying games that did not use an existing setting. However, the biggest science fiction roleplaying games have used existing licenses, from longtime stalwarts Star Trek and Star Wars (each of which has existed in a variety of mechanical systems from a variety of publishers). Perhaps Starfinder will change that trend, but historically that’s how it’s been – you don’t sit down to play a “science fiction” RPG, you sit down to play an RPG about a show or book or movie you like.

I give that introduction because I’m writing about the John Carter of Mars roleplaying game, published this year by Modiphius Entertainment. John Carter of Mars is, obviously, a licensed science fiction roleplaying game (the books by Edgar Rice Burroughs; I’m guessing not so much the flop of a feature film). But it’s a license that I approach knowing virtually nothing about – I haven’t read the books (and I definitely haven’t seen the movie). So this review is not going to approach the roleplaying game from a “does it feel like or reproduce the books” point of view, but purely from the roleplaying fun side of things. The physical book is a 280+ page hardcover, with a distinctive landscape orientation.

What I can tell you about John Carter is that he was a pulp adventure hero created by Edgar Rice Burroughs (who also created Tarzan) and first introduced a bit over 100 years ago. For purposes of this review (or playing the game, really) it’s kind of unimportant who John Carter was or where he came from (the characters in a pulp adventure RPG need to be hogging the spotlight, not ceding it to some character from a novel). What is important is that he come from Earth and ends up on Mars, where he meets a variety of Martian subraces, then proceeds to exhibit physical, mental, and social skills such that he makes allies, wins battles, marries the princess, exposes the planet’s sham religion, and becomes the leader of basically every part of Mars worth leading. His children also start in later books in the series. The world of John Carter is also rationalist. Evil is caused by ignorance and selfishness. Religion is a den of lies. Without the actions of the heroes, evil will overrun society – but with the inspiration provided by heroes all but the worst people can be brought to see the error of their ways (and the worst of the worst will often be apparent due to their love of torture, racism, cannibalism, and such).

It is that pulp adventure Mars – called Barsoom by the natives – that the characters will inhabit. Most players will be natives of Barsoom. One (or at most two) can be from Earth, who came to be on Mars via a hearty helping of who-cares-that’s-just-how-it-is. The vibe of the game is defined in no small part by having the characters being omnicompetent at being whatever they are. Mechanically, this means that the game has no skills, as they’re traditionally conceived of. If a doing a thing is in the milieu of what that sort of character might be familiar with, then they can do it. If someone teaches them to do it, then they can do it. Easy peasy. They also generally will not be as held back by the fear of injury, as Martian medicine is able to cure pretty much anything. Characters in John Carter of Mars are intended to be bold and proficient, and their adventures epic in scope, possibly changing the course of the planet’s history.

Barsoom is, to some extent, a dying planet – but it is a death that has long been held in abeyance by technology, and that moved further away through the actions of John Carter. In most ways, Martian technology is more advanced than Earth’s, with rayguns, airships, holograms, and food tablets (in addition to medical advances). Development of new technology, however, is quite limited – they primarily rest on the glories of the past. Martian culture is fairly martial in outlook, including matters of honor – so there’s a lot of physical conflict, but it can be limited in nature (for example, it is dishonorable to defend yourself only with an equal or lesser weapon; so if you’re attacked with a sword, it would be dishonorable to shoot your attacker). This means that Martians do not always use all of the technology at their disposal.

For those a bit familiar with Barsoom, note that there is background on the stories of the books, information on setting the game within different periods (when Carter first comes to Mars, when he becomes a prince of one city, and when he becomes the warlord of basically the entire planet), and stat blocks for the main characters of the books so they can be run as player characters (or guest star as NPCs). There are also information on hidden kingdoms and races not available in the standard player character options (discussed below). The book also takes great pains to emphasize that, while the original stories of Barsoom tended depict strict gender roles and to limit female characters to the role of damsel in distress, players are encourage to dispense with this relic of the source material.

Basic Mechanics

Because there are no skills, rolls are typically based on attribute + attribute. John Carter of Mars uses a significantly modified version of Modiphius’s 2d20 system (they always modify it a lot to fit the world being played, so something like John Carter 2d20 feels way different from Star Trek 2d20), so that means rolling some d20s (by default rolling two, as one might guess from the name of the system, but there are lots of ways to add bonus dice). The target number is the sum of the two attributes – roll the target or less, and that’s a success. The difficulty of the task adjust the number of successes needed. The average starting attribute is 6, so the ‘average’ target would be a 12 … but, of course, characters will tend to do what they’re good at and players will tend to try to use attributes that make them more likely to succeed, so in reality the odds will be better than that. Additionally, each die is equal to or lower than the lower of the two attributes counts as two successes (this should produce bonus successes much more often than the similar aspect of other 2d20 games).

Another concept that is central to the system is Momentum/Threat. Players can spend their Momentum to get benefits (note that, unlike some other 2d20 games, Momentum in John Carter is personal, instead of being available for the whole party to spend), while Threat is spent by the GM for their nefarious purposes. The basic way of gaining Momentum is through extra successes on a test – so characters taking straightforward actions that they’re really good at can really rack up Momentum. Momentum can be immediately spent for benefits on that roll, or banked for later. The most common use of Momentum is to spend one to get an extra d20 on a roll (this only works with banked Momentum, because the spend has to come before the roll). Damage can also be boosted. Momentum can increase the difficulty of enemy’s tests, which costs two Momentum. It can also be used to make a success better or broader in scope, but the cost and effect of such a spend will vary from test to test. Threat is spent to similar effect as Momentum, creating opportunities for enemies or hampering the PCs. Threat can also be used to let enemies win ties on opposed tests (player characters usually win ties). The GM starts with a few Threat each session, but can gain more if the players roll natural 20s, or if players generate Threat in place of Momentum they don’t have.

Character Creation

As with many tabletop RPGs, the first formal mechanical step of character creation is starting attributes, but there’s a good chance players will pick a race/archetype combination and then go back to select attributes.


There are six attributes – Cunning, Daring, Empathy, Might, Passion, and Reason. Characters start with a 4 in all of the attributes, and might have an attribute as low as 3 (which is still considered average, from a conceptual point of view – a character is never conceptually bad at an attribute unless you work at it). The race and archetype choice will spread out a net of 8 points, while the archetypes will hand out another net +4. The archetype boosts are locked, but only some of the racial boosts are, and players also effectively get an extra 4 points to put wherever. By default, attacking always uses the Cunning attribute, so expect that to be pretty universally high.


The five races available for player characters are Earthborn (Jasoomians) and martians of the green, red, black, and yellow varieties. Visually, all of the Martians (except green Martians) look pretty much exactly like humans, but without body and with vividly colorful skin (the Martians lay eggs, but somehow this doesn’t change their visible anatomy at all … and almost all of their anatomy is visible, because Martians only wear clothing to the extent necessary to appease Jasoomian censors). Much like human “races,” all of the Martians (again, except for the green) are all one species and capable of interbreeding (“mixed heritage” characters, including Martian/Earthborn, are an option).

Red Martians are something of a default choice. In the novels, they’re the first non-green Martians that John Carter runs into, sort of the civilized side to the green ‘savages.’ The other colors of Martians are added later, found in secret cities and the like. Red Martians get pretty flexible attribute boosts, while the yellow and black varieties get at least some of their boosts pushed into Cunning and Daring. However, in ‘mechanical’ terms, the biggest difference between the three is What You Know and What You Can Do. As noted above, there are no skills. So ‘what you can do’ is pretty important in defining, well, what you can do (although the similar section in the archetype is probably more important). So all three types of non-green Martian know the basics of self-defense, use of basic machinery and medicine, and operation of vehicles and mounts. Red Martians know the basics of red Martian culture, science, and politics; but they know basically nothing about the other non-green Martians. The yellow Martians (also known as Okar), on the other hand, know a lot more about ancient history and a lot about surviving in the arctic (but nothing about hot climates). Black Martians (also known as First Born) are generally more skilled in deception, know more science, history, and religion – but not about the customs of the ‘lesser’ Martian races.

Green Martians, by contrast, don’t look human at all. They’re 10-15 feet tall. They have four arms. They have tusks. They don’t have noses. Their culture is defined by tribal hordes. They do not start out knowing how to operate machinery or use vehicles.

Earthborn are buff, starting with an enhanced Might attribute (thank you, higher Earth gravity). They know the basics of personal combat and can perform tasks that have a clear Earth analog (e.g., shooting a gun), but that’s about it. They can, however, learn about Martian culture, science, and such fairly quickly. Later in character creation, Earthborn will get more Talents than other races, but start without any renown or equipment.


There are 15 archetypes, so there’s a lot of selection. In addition to the attribute bonuses, each provides a Grade 1 Talent and and very important list of things you know and can do. For example, the Gladiator knows about melee weapons, the environment, and beasts, and can fight like crazy, exploit others during combat, and play to a ground. On the other hand, the Airship Officer knows about airships, airship combat, and Martian militaries, and can fly anything there is to fly, command and repair airships, and fight in close quarters or with ship-based weapons. The full list of archetypes is Airship Officer, Assassin, Beastmaster, Duelist, Envoy, Explorer, Fugitive, Gladiator, Guide, Healer, Panthan (mercenary), Rogue, Scientist, Soldier, and Spy. Custom archetypes can be created as well.


Talents can do a bunch of things. While there’s a solid list of them included, they can also be custom-crafted for almost any sort of action, including the creation of combo-talents that have multiple effects. A talent is supposed to be semi-specific, but still come up pretty often. So attacking is too broad, but attacking with a gun is just fine. Grade 1 talents can add a d20 to an action, make a particular attribute applicable no matter what (so you can be terrible at a certain type of action, but use a talent to always force it to what you’re good at), do extra damage, avoid dangers, or get an answer to a yes/no question. Grade 4 talents can grant an extra Conflict action or automatically remove afflictions. One thing I was not a fan of, however, was how they explicitly not upgradeable and not combinable (you can have one talent that does multiple things, but not apply multiple talents to one action). So at some point you have to decide whether to spend XP now to get a decent talent, or hoard XP to get a super-talent later. But the multi-talents are really, really good – the fact that you’re being forced to “buy” the talents again to combine them seems it’s supposed to “balance” the power level of the multi-talents. This would drive me batty as a player – I would hate having to repay for an ability, so I would just end up sitting on a pile of XP until some indefinite point in the future when I was going to buy my super-talent. I think I would want to see a narrator allowing “upgrades” of existing talents, but then having a quick veto pen to stop “mega-talents” from getting out of hand.

Other Mechanics/Content

Conflict in John Carter of Mars is fairly abstracted, which things like distance abstracted into five zones (immediate, near, away, far, too far). In action scenes, characters basically get your traditional move + attack per round. Melee attacks default to Cunning + Daring, while ranged attacks use Cunning + Reason. The book says that Daring is commonly used to resist attacks, but that seems much more susceptible to players defending how they want.

Damage is a bit complicated, because characters have three damage tracks – confusion, fear, and injury. Where the character takes the damage depends on what they used to defend (player’s choice if there are two options) – Empathy/Reason relate to confusion, Daring/Passion relate to fear, and Cunning/Might relate to injury. Characters initially take stress on these three tracks, and stress typically just requires rest to recover. But when a lot of stress is suffered at once, or a stress track is filled (the stress track is equal to the higher of the two associated attributes), then the character takes an affliction (which increases the difficulty of all rolls using the associated attributes).

Renown tracks how respected and well-known a character is (renown is spent, but the total earned is also used to track fame). Renown can be spent to obtain ‘accolades’ – allies and titles that cement their influence on Barsoom.

The book includes a bestiary for the characters to encounter in the Martian wilderness, as well as an array of NPC stat blocks to fill out more ‘civilized’ encounters (you know, where they kill you with words and guns instead of teeth and claws). An introductory adventure (the Mind Merchants of Mars) can be used to show players the ropes (both mechanically and for the setting).


So if, like me, you aren’t specifically in the market for a John Carter roleplaying game, is there a draw to play the John Carter of Mars Roleplaying Game? I think there is a draw, and it’s the epic pulp planetary romance. Pulp adventure has had something of a resurgence in roleplaying game of late, but there are a lot of different kinds of pulp adventure. Noir detective stories, lost civilizations in the jungle, and the weird west can all be pulp adventures, but they’re all a lot different from the more epic scale of Barsoom. And, as always, Modiphius goes the distance to customize its 2d20 system to fit the world and themes being presented. If you find the idea of a group of highly competent heroes rising from small beginnings to having planet-shaping adventures appeals to you, then you’ll want to give John Carter of Mars a try.


Promotional consideration was provided in the form of a review copy.

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