
- BGG rank
- BGG #2,692
- BGG rating
- 8.0
Infinity N3: Core Book
- 2 players
- 90–120 min
- Complexity 3.9/5
- 2005

Expansion for Warhammer: The Horus Heresy – Legions Imperialis
2024
Rules assistance for Warhammer: The Horus Heresy – Legions Imperialis: The Rise of the Dark Mechanicum
Plain-language explanations of turns, card effects and disputed situations, with official source references and saved question history.

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Answers come from the official rulebook, with the page to check.
Warhammer: The Horus Heresy – Legions Imperialis: The Rise of the Dark Mechanicum is an expansion for Warhammer: The Horus Heresy – Legions Imperialis released in 2024 for 2–6 players, 120 minutes per game, and ages 14 and up. Its main mechanics are Dice Rolling and Order Counters.
During the Age of Darkness, the Mechanicum of Mars split in two, just as the Astartes did. Fueled by righteous fury on both sides, they tore into each other with the most devastating weaponry unleashed during those bleak times, holding nothing back. Contained within this 128-page hardback book you will find a comprehensive history of the rift that tore the Mechanicum apart, detailing the corrupt technologies employed by the Dark Mechanicum, as they came to be known. You'll learn of the Doom of Magma City, the largest conflict of this internecine war, and the forces that took part. Also included are rules for both the loyal Mechanicum, and the traitorous Dark Mechanicum, plus their Formations, and Detachments. This supplement book presents a full campaign system for linking Legions Imperialis battles together, including an Escalation Campaign that sees the forces ramping up to a final apocalyptic battle. You'll also find rules for three Formations of Legend, with their own unique special rules, plus army lists for Collegia Titanica and Questoris Familia forces. —description from the publisher
Warhammer: The Horus Heresy – Legions Imperialis: The Rise of the Dark Mechanicum supports 2–6 players according to the catalogue. This range comes from the publisher’s listed player count, so the game can be set up for any group size within it. Some setups, rules and scoring details may still vary by player count, so check your edition’s rulebook for the exact configuration.
The listed playing time for Warhammer: The Horus Heresy – Legions Imperialis: The Rise of the Dark Mechanicum is 120 minutes. This is the publisher’s estimate for a full game. The actual duration depends on the group, the player count and familiarity with the rules: first sessions usually run longer, while experienced groups often finish faster. Setup and teaching time are not included in this estimate.
The catalogue lists Warhammer: The Horus Heresy – Legions Imperialis: The Rise of the Dark Mechanicum for ages 14 and up. This is the publisher’s recommendation and reflects reading demands, rule complexity and small components rather than theme alone. Younger players can often join with help from an adult, so check the age guidance on your edition and consider your group’s experience with board games.
Warhammer: The Horus Heresy – Legions Imperialis: The Rise of the Dark Mechanicum belongs to these categories: Miniatures, Science Fiction, and Expansion for Base-game. Its main mechanics are Dice Rolling and Order Counters. Categories describe the theme and setting of a game, while mechanics describe what players actually do on their turns. Each mechanic links to a catalogue hub with similar games, which helps when you want something comparable.
The catalogue lists Warhammer: The Horus Heresy – Legions Imperialis: The Rise of the Dark Mechanicum as an expansion for Warhammer: The Horus Heresy – Legions Imperialis. Expansions add new content, rules or scenarios to the base game and usually cannot be played on their own, so you need Warhammer: The Horus Heresy – Legions Imperialis to use it. Check that your edition of Warhammer: The Horus Heresy – Legions Imperialis is compatible, as some expansions were revised between editions.