Coriolis: The Great Dark Arrives from Free League

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Free League is heading into the darkest depths of space with Coriolis: The Great Dark, a new sci-fi TTRPG which follows a band of human colonists in a remote region of the galaxy filled with ancient alien ruins, a mysterious plague and unexplored worlds.

Technically, The Great Dark is a new edition of Coriolis: The Third Horizon, the award-winning but often overlooked RPG which Free League released back in 2017. The Great Dark, however, marks a radical departure from its predecessor, both in terms of mechanics and overall tone. Where Third Horizon was hailed as a swashbuckling adventure inspired by The Arabian Nights, The Great Dark is grittier in nature, drawing inspiration from early 19th century explorers, deep sea divers and pulp archeology.

A PDF version of The Great Dark Core Rules was released this past August on DriveThruRPG, but the hardcover is now available from local game stores and Free League. Below, we suit up and take a look at all the details.

What is Coriolis: The Great Dark about?

Coriolois: The Great Dark is a new TTRPG that was launched after a successful Kickstarter back in early 2024. The setting is focused on a futuristic diaspora of human refugees who arrive in a remote system which they call Jumuah. They eventually settle on a large asteroid, converting their armada of ships into a new settlement which they name Ship City.

The colonists, however, soon learn that the nearby systems were once home to an ancient, long extinct alien civilization and are now filled with mysterious ruins and powerful artifacts. Unfortunately, they are also home to the Blight, a bizarre plague that warps the mind and bodies of those it afflicts.

Years later, the settlers are soon divided into various factions, including: Machinists (who build and maintain the colonists’ technology), Gardeners (who cultivate food and manufacture breathable air), Navigators (who command large vessels known as Greatships) and Explorers (who brave the cold vacuum of space in search of ancient artifacts). Players take on the role of the latter, forming crews who use high-tech “delver suits” to venture into the darkness, exploring ancient astronomical ruins and facing terrifying creatures warped by the Blight.

Technically, the new setting does take place in the same universe as Coriolis: The Third Horizon, but is several hundred years in the future and for all intents and purposes is really a new setting that requires no previous knowledge of past Coriolis products or lore.

Mechanically, the rules of the game are based on Free League’s Year Zero Engine (which is also used in the Alien RPG and Twilight 2000). The game uses a dice pool system, with players rolling a number of six-sided dice based on their skill and attribute levels, with a roll of 6 indicating success and extra sixes adding bonuses. Characters can also tap into push mechanics, which lets them re-roll failed dice while also acquiring stress or damage that can lead to further consequences down the line.

What’s included in the “Coriolis: The Great Dark Core Rulebook”?

The Great Dark Core Rules is a 308-page book that contains the following:

• Character creation rules with detailed options for Explorere talents, vehicles, and crew maneuvers.
• Exploration rules for traveling on Greatships through the dangerous Slipstream, and visiting unexplored planets.
• A detailed gazetteer on the eleven systems that make up the Charted Sphere and the asteroid-metropolis of Ship City.
• An intro adventure called The Black Ziggurat that takes place in a set of ancient ruins on a mysterious distant moon.
• Solo play rules that allow you to Explore and run complete adventures in Coriolis without a GM or other players.

How much is the “Corilois: The Great Dark” Core Rules?

The hardcover retails for $57.42 USD (not including shipping and handling), while the PDF is available for $24.99 USD. A Foundry VTT version is also available for $29.67 USD. Notably, there are also a few extra accessories, including a GM screen (which retails for $27.52 USD) and a custom dice set (which retails for $23.25 USD).

When was “Coriolis: The Great Dark” released?

The new hardcover of the core rulebook was released on October 27th, 2025, while the PDF was released earlier this year on August 14th, 2025 (notably, individuals who backed the original Kickstarter also received PDF copies earlier in 2025).

Why is Coriolis: The Great Dark worth picking up?

If you’re on the fence about The Great Dark, there a few reasons why you might consider grabbing the core rules.

• A unique setting: There are a ton of sci-fi TTRPGs on the market, but The Great Dark feels new and innovative, with atmosphere and lore that hasn’t really been explored in many other games before.
• Stunning artwork: Not surprisingly, Free League looks to have created some absolutely incredible illustrations for The Great Dark, which help to establish the sense of dread and strange hopefulness the setting is going for. If nothing else, it’s worth having as an art book.
• Great for new and returning fans: If you’re a player of the original Coriolis: The Third Horizon, chances are you’ll dig the new direction they’re taking the game in. Conversely, if you’re new to the setting, it’s the perfect time to jump in.
• The Year Zero Engine: In a market cluttered with chunky and cumbersome TTRPG rules, Free League’s YZE is simple, streamlined and easy to use, and it’ll be interesting to see how they evolve it with new mechanics that build on the themes of The Great Dark.

Final Thoughts

With its brooding atmosphere and gritty sci-fi vibes, Coriolis: The Great Dark looks like it has the potential to become a hit for Free League, reaching the audience the original Coriolis: The Third Horizon RPG never quite achieved. Whether or not TTRPG players are willing to head into the darkness, however, remains to be seen.

You can pick up the The Great Dark Core Rules now from your local game store, DriveThruRPG and Free League.