A Non-Review of the Coriolis RPG

Posted: 2020-09-24
Word Count: 3873
Tags: coriolis non-review rpg year-zero-system

Table of Contents

This wil probably be my last post on Coriolis at least for a while. (I’ll turn my attention to Vaesen soon.)

The latter more-than-half of the Coriolis Core Book details the sprawling and atypical science fantasy future of the Third Horizon. The authors liked this setting1 so much that they named their company after one of the factions. But it’s the player-facing rules that shape the game experience. So I’d like to compare these rules to the later Alien RPG, which I previously didn’t review. Then I’ll expand on the setting. In doing so I hope to explain why this setting inspired not only unique mechanics but a 400-page book and the name of a game company.

Character Rules

In another post I walked through character generation. To summarize:

  1. All players pick a Group Concept, which encapsulates their mission and the general bent of the campaign and grants them some benefits.

  2. Players pick a Ship that fits their mission. They can use one of twelve pre-built ones – three variations on four basic designs – or they can build their own.

  3. Players then create characters much as any other Year Zero Engine game, starting with an Archetype Character Concept and filling in details.

There are a few notable differences, e.g. a greater number of skills, half of which are “Advanced” and can’t be used unless the character puts a point into them (or has a special Talent). But Combat feels familiar, especially to those who’ve read the rules of Alien or Mutant Year Zero. If the weapons and other tech differ in details2 they serve very familiar purposes.

Having read more background, though, I’d like to delve into places where setting details become game mechanics that heavily influence the player’s perspective.

The Icons

The Icons, the gods of the setting, are deeply embedded in the setting. All religions revolve around the Nine Icons or local versions of them. The Third Horizon’s calendar is divided into segments named for them. They’re also embedded in the mechanics of Coriolis.

Praying to the Icons

Coriolis renames the Year Zero Engine’s “pushing a roll” mechanic to “Praying to the Icons”. When players decide to reroll their dice3, their characters momentarily pray to the Icons.

This isn’t just a name change. Every Skill in the game has a corresponding Icon attached to it. The Dancer has Dexterity (and Melee Combat), the Traveler has Survival and Culture, the Merchant has Manipulation (i.e. convincing people to do things), etc.4 If the characters have previously spent game time praying to the Icon that governs that particular skill, they gain an extra die5 on the reroll.

Icon Talents

As mentioned before, the Icons also play a role in character generation. At character creation, the GM randomly determines the character’s ruling Icon. Each Icon grants characters a specific Talent they can invoke once a session. For example:

And so on … a mix of miraculous escapes and inexplicable triumphs, which bypass the usual mechanics and verge on meta-gaming. Each of them, alas, requires paying a Darkness Point.

The Icon Deck

The Icon Deck is a purely optional play aid, and rolling dice on an appropriate random table works just as well. Like decks for Free League’s other games, however, it’s also an evocative prop and a useful alternative to dice.

Thirty-six cards represent the nine Icons (four times each), and they have the following uses.

The Icon Deck also contains cards to identify and describe the five crew positions in starship combat, plus twelve NPCs.

The Darkness Between the Stars

In the Third Horizon, the Darkness Between the Stars isn’t merely interstellar space. It’s a malevolent force or entity that causes curses and bad fortune. It spawns monsters in the Void. Some say it’s responsible for cursing people with mystic powers. The Icons can keep it at bay, but only so long. Look too long at the Black, and it looks back at you …

In Coriolis, it’s not just old spacers’ tales. It’s represented directly by the GM’s pool of Darkness Points.

Gaining Darkness Points

Certain player actions give the GM darkness points, namely:

So, to avoid Darkness Points, players must accept the dice as they’re rolled, never use the blessings of their Icon Talents, and avoid portals, deep space, unexplored planets, areas with sinister reputations, and accurséd alien ruins.

But what fun is that?

Spending Darkness Points

A GM can spend a Darkness Point for the following effects:

With one or more Darkness Points an NPC can do things they normally can’t, e.g.

Other things cost multiple Darkness Points, such as:

Most of these a modern person would dismiss as bad luck. (Or violations of adventure story tropes.) Only a few hint at supernatural malevolence: madness, the implied curse of quasi-psychic powers, and the powers of alien or supernatural entities getting stronger because somebody had to make that one impossible shot.

Note that the Fate System has Fate Points with which players and GMs alter die roles, add narrative details, and (in the GM’s case) compel flaws. Darkness Points seem like a GM-centered inverse of Fate Points, a narrative debt that only players create and only the GM calls in. Life in the Third Horizon is hard.

How Mechanics Shape Experiences

The Alien RPG’s primary mechanical innovations were

  1. the Stress mechanic, which attempts to recreate the movies’ suspense and reflects characters’ fear and fight-or-flight reactions.8

  2. Cinematic Play, which enables one-shot scenarios with paranoia and secret agendas.

So how do Coriolis’s mechanics shape the players’ experience? Mechanics tied directly to the Icons and the Darkness reinforce the mystical and fantastic aspects of the Third Horizon.

  1. Blessings, prayer, and religious rituals have in-game effects. Through various rules the Icons put the odds in the players’ favor and let them win (fleeting) success.

  2. Likewise the Dark Between The Stars has a pool of points, perhaps physical tokens piled in front of the GM, each one added when the players previously put the odds in their favor or tampered with the unknown.

  3. Darkness Points, in particular, reinforce the dangers of space travel, using mystical powers, trespassing in ancient ruins, and meddling with alien artifacts. “Tempting fate” takes on a literal meaning.

Characters might strive to be masters of their fate, but they’re caught between opposed forces dispensing fortune and misfortune. Fate has a name … and rules.

The Firstcome culture in Coriolis is clearly post-Islamic, Arabia mixed with bits of North Africa and South and East Asia. Yet Coriolis’s mechanics reflect a fatalism characteristic of the Muslim world, perhaps by way of Herbert’s Dune: the universe is far bigger than mankind, and forces beyond comprehension shape our fates. In the Western world such attitudes inspire horror – witness the entire oeuvre of H. P. Lovecraft and his imitators – but in other cultures it also inspires wonder.

The scientism and positivism of the Zenithians – a stand-in for Western commercialism and colonialism – seemingly ignores the capriciousness and cruel ironies of fate embedded in the game’s very mechanics. Yet they also reflect the (mostly European or American) players’ optimism, their ultimately fulfilled assumption that their characters’ actions have meaning and influence in the game world. Coriolis is a stage to play out stories of a small band of adventurers in a medium-sized starship somehow, almost by accident, changing the fates of worlds. The Arabian Nights, the touchstone for Coriolis, is an anthology of tales in which Sinbad and other heroes brave a hostile universe full of monsters and evil spirits yet triumph; it’s also a meta-narrative of a clever woman, Scheherazade, outwitting and beguiling a mad prince to save her life just one more day until she at last wins freedom and fortune.

The ubiquity of the Icons and the effects of Darkness Points, I suspect, not only provide consequences for players (legally) fudging the dice and nudging their characters’ stories. It’s the interplay of forces in adventure fiction and role-playing games writ large: players portraying extraordinarily competent characters who beat the odds and an all-powerful GM who could throw anything she wants at the characters but restrains herself so that together they can tell interesting stories.

Starship Rules

Another post covered Coriolis space ship statistics and generation. Reading those rules, however, I’m struck by how Alien’s rules seem like watered-down versions of Coriolis’s (Which makes sense, as Coriolis came first.)

Ship Modules

Coriolis’s ship creation rules are, as previously shown, very detailed. Modules and features include not only expected elements like compartments, weapons, and functional upgrades but, for example, a chapel to pray to the Icons, databases and computer upgrades for scientific and cultural research, an arboretum within which a character restores their mental health more quickly, and a “blessing” to make portal transit smoother. Ships in Coriolis aren’t just transport; they’re homes and works of art.

Alien uses a broadly similar system, but (as I recall) with fewer options. Its “modules” are essentially units loaded, unloaded, and reloaded into pre-fab standard hulls. Ships in Alien (RPG and series) are brutalist and purely functional, albeit occasionally unreliable, reflecting the Corporations’ pursuit of profit over human lives.

Combat Phases

Ship-to-ship combat in Coriolis, as in the later Alien RPG, assumes only one or two ships (plus assorted missiles) on each side. It therefore only tracks ships proximity to each other on a one-dimensional “map”. (See my Alien non-review for slightly more elaboration.)

Each position on the crew – Captain, Engineer, Pilot, Sensor Operator, and Gunner – has their own phase in a round of Space Combat. The five phases of combat are, in order:

  1. Order Phase: each Captain (PC and NPC) gives secret orders, which are broadly ATTACK!, RETREAT!, EVADE!, or REPAIR!. The Captain also rolls his Command skill, and the degree of success grants that many extra dice to actions in line with their orders.

  2. Engineer Phase: each ship’s Engineer allocates Energy Points (EP) to ship systems, including engines, weapons, and sensors. Systems without sufficient EP will not work. In combat “system damage” reduces the EP available each turn, at which point the engines cannae take it and the Engineer must make hard choices.

    Also in this phase, each Engineer and crewperson not otherwise engaged gets one action to effect repairs, to overload the engines for more EP but also more structural damage, or to open an airlock during boarding actions.

  3. Pilot Phase: each Pilot makes a Pilot skill test to move closer or further away from the enemy, to perform evasive maneuvers, to position the ship so it can act sooner next turn, or to ram or board a vessel.

  4. Sensor Phase: each Sensor Operator makes a “Data Djinn” (info-tech) test to get a target lock on one enemy, break one enemy’s target lock, launch a pulse attack that does EP damage to one target, or (if the ship is capable) engage stealth mode.

  5. Weapons Phase: each Gunner fires a weapon system, launches a torpedo, or drops mines.

Class III ships and larger, like the PCs’, require a minimum of five crew to run effectively. If there aren’t enough PCs for all five positions they’ll have to invest in automated systems, hire NPCs for the missing positions, or take the penalties9 for multiple actions a turn. A smaller ship can combine positions without incurring penalties, with some restrictions. E.g. only certain positions may combine as the number of crew drops10, and the Captain can’t grant Command bonuses if he’s also flying the ship11.

In contrast, Alien’s phases were, roughly Captain (orders only), Sensors12, Pilot, Weapons, and Engineer (repairs only13). Each crewperson still had only one action per turn, but (for example) the Captain’s role of giving orders and deciding initiative don’t really count as actions as far as I can tell. No doubt some of that comes down to genre differences: the Alien franchise isn’t known for its space battles.

Giving all the players something to do during ship-to-ship battles makes sense, and I’ve seen that approach elsewhere, notably in Swashbucklers of the 7 Skies. As noted previously, not every gaming group has five players. In practice, one or more players probably roll for the NPCs or Ship Systems.


As I said, this is well over half the book, not to mention supplements that detail individual planets, or explore the factions and their proprietary technology.

As I touched on previously, the Third Horizon consists of thirty-six planetary systems linked by alien portals that allow ships to travel between them along specific routes. The original human settlers, the Firstcomers, came from other human-settled clusters – the First and Second Horizons – and then lost their gateway back in a devastating war. The Third Horizon then fell into a dark age during which only the rich or extraordinarily dedicated pursued interstellar trade and travel. About 60 years ago the slower-than-light generation ship Zenith arrived in the Kua system … to find humans already living there. After a furious internal debate that split the Zenithian’s crew/leaders, they thawed out their colonists, converted the Zenith into the space station Coriolis, and reverse engineered the Firstcomers’ spaceship technology to forge sprawling commerical empires.

The cultural split between the traditionalist and deeply religious Firstcomers and the commerce-oriented and scientific Zenithians drive a lot of the Third Horizon’s politics, economics, and culture. Rifts between and within each of these groups created factions who dominate interstellar relations. Zenithian factions include the economically imperialist Consortium (which dominates Coriolis), the elitist Zenithian Hegemony that presides over the sprawling Conglomorate on Kua, the Free League of smaller companies challenging the Consortium’s various monopolies, and the Legion, formerly Firstcome mercenaries and militias now banded together and allied strongly with the Consortium. The Firstcomers are likewise split among the Church of the Icons, a relatively new organization imposing its own doctrines and structure on the Horizon’s local beliefs, the fanatical Order of the Martyr whose gentler subsidiary the Samaritans mask a militant, intolerant theocracy, Ahlam’s Temple which is known for its graceful courtesans (and suspected of training even more graceful assassins), and the Nomad Federation which attempts to unite diverse Firstcome clans and organizations, including a massive flotilla of civilian spaceships, and frequently fails.

Politics among the factions filter down to the lives of ordinary citizens – and player characters – only indirectly, as the backdrop for various freelance jobs for which middlemen might hire ruffians with a ship. A few sections describe culture and life for ordinary people. In summary, it’s about what you’d expect when isolated and somewhat impoverished cultures ruled by entrenched petty nobles meets an expansionistic, corporatist, technocratic culture. There are art forms reminiscent (and probably inspire by) various cultures across our contemporary Muslim world and East Asia … and there are all too familiar disparities in social status, wealth, and technology14.

The Third Horizon also features numerous indigenous cultures, some of which have a few alien “semi-intelligences” that either mind their own business or skulk at the outskirts of human civilization, mysterious artifacts possibly left by the unknown Portal Builders, and, inevitably, monsters. These last range from alien fauna to forgotten war machines on the edges of explored territory to creatures spawned from the Darkness Between the Stars to actual djinn and spirits. (“Arabian Nights in space”, indeed.)

While the mechanics put an interesting spin on space opera, the extensive background gives GMs a lot of material to mine. If I run Coriolis, I might not run it exactly as written – My Third Horizon Will Differ – but I hope I can maintain the dangerous, quasi-mystical, decidedly non-Western influences that distinguish Coriolis from Alien’s grim techno-horror, the Flash Gordon meets used future meets Zen laserswords of Star Wars, and the hodgepodge of mostly American influences in Traveller’s Imperium and its many successors.

Appendix: Success Probability Table

For reference, the table below shows the probability of success based on the number of dice rolled.

Dice Chance With Prayer Critical15 Critical With Prayer
≤0d16 3% 9%
1d 17% 31%
2d 31% 52%
3d 42% 67% ½% 3%
4d 52% 77% 2% 9%
5d 60% 84% 4% 17%
6d 67% 89% 6% 27%
7d 72% 92% 10% 37%
8d 77% 95% 13% 46%
9d 81% 96% 18% 55%
10d 84% 97% 23% 63%

This version corrects Table 3.3 on page 58 of the core book. The “With Prayer” column in the book is off by a few percent. Many have pointed this out; the table comes originally from Mutant Year Zero, in which a 1 on the die prevents a player from rerolling that die, whereas Coriolis has no such rule. See the analysis here.

I’ve also included chances for a Critical Success, based on calculations done here.

Corresponding tables in Tales From the Loop and Things From The Flood require similar corrections. The one in Vaesen, on the other hand, is correct.

  1. Apparently embodied an older game that inspired them to adapt it to their house system when they finally got the license. ↩︎

  2. I still can’t quite wrap my head around how the setting’s communications and information technology relates to how real-world tech works, e.g. why someone would prefer a “tabula” and/or personal holograph to a full computer and/or a surface-to-orbit communicator. (Answer to the last: it’s heavy, and some planets don’t have stations in orbit that can or will receive.) But then I was also late to the smartphone / tablet revolution too. ↩︎

  3. Unlike other YZE games, ones have no special significance. Players can reroll any die not showing a six. This alters success chance probabilities a bit. ↩︎

  4. Some associations seem a little obscure. The Judge has Command and Ranged Combat, I guess as dispenser of justice. The Messenger has Data Djinn (communications and info-tech) but also Science and Technology which maybe also come from the Icons? The Gambler has Observation and Pilot, maybe to seize lucky breaks and act on them. ↩︎

  5. If they prayed in the ship’s chapel, which is a thing ships have in this setting, they gain two dice on the reroll. ↩︎

  6. This can have more immediate effects too, called “hypersickess” or “bad stasis”: temporary mania, twisted limbs. The rules aren’t clear whether this happens to PCs directly, or whether Darkness Points are a stand-in for sickness that happens later. ↩︎

  7. Which may seem a little harsh, but it’s a variation on discovering Things Man Was Not Meant To Know in cosmic horror settings like the Cthulhu Mythos or the Alien franchise. ↩︎

  8. Coriolis, by the way, has a different mechanic for Stress: Mental anguish, stun weapons, and the rigors of combat wear down a character’s “Mind Points” which work essentially like “Hit Points”. When Mind Points reach 0 the character is simply incapacitated; rest restores one MP an hour. Compare to Vaesen and other games where characters can be mentally Broken, and suffer all sorts of unpleasant effects↩︎

  9. Specifically, -2 dice per extra action to each action. Someone trained in a task typically rolls 6 to 8 dice, so chances of success drop by 10% or more for each extra action … absent a whole lot of prayer and accumulated Darkness Points. ↩︎

  10. Specifically, first Captain and Pilot combine (four), then Engineer and Sensors (three), then Captain/Pilot and Gunner (two). Only a Class I ship like a fighter can get by with one person performing all roles (and rolls) without penalty. ↩︎

  11. The captain who sits behind the pilot and shouts orders but doesn’t actually pilot the ship is very reminiscent of Firefly (listed as an inspiration in the first chapter), Star Trek, and some iterations of Battlestar Galactica↩︎

  12. Why Sensors go after Pilot in Coriolis is a mystery. Maybe the Pilot might like to know about other ships lying in wait? ↩︎

  13. In the Alien RPG ships didn’t run on Energy Points; if the reactor is still running, everything gets power. ↩︎

  14. The rules categoize technology as Advanced, Ordinary, and Primitive, plus Faction technologies jealously guarded by the factions. Advanced is cutting edge, found mostly at Coriolis and the Zenithian Hegemony’s citadel, the Monolith. Oridinary is an amalgam of Firstcome and Zenithian advancements, found at most orbital and planetside settlements, although maybe not all neighborhoods. Primitive is jerry-rigged or archaic holdovers from initial Firstcome colonization found mostly among forgotten tribes and failing colonies, and includes everything from axes to muskets to computers with keyboards. ↩︎

  15. Three or more sixes on a skill test is a Critical Success; this usually grants some extra benefit specified in the skill. See pp 54 and individual skill descriptions in the core book. (Except in combat, where each extra six “buys” a bonus effect like increased damage, inflicting a critical injury, or disarming the enemy. Also, in opposed rolls, the side that rolls more sixes prevails.) ↩︎

  16. According to the Zero Dice rule on page 59, If your modifiers put you at zero dice or fewer, roll two dice — but to succeed, both have to show sixes. It’s equivalent to a “Challenging” roll on two dice, as described here↩︎