Changes

|source = From the final testament of [[Sulem Rei]], historiarch of the Imperial Court, presented to the [[High Lords of Terra]] circa 098.M32{{Fn|2a}}

}}

Largely the work of [[Alan Bligh]] and [[John French]]{{Fn|5b}}, the player commands an army of [[Forge World (company)|Forge World]] and [[Citadel Miniatures|Citadel]] models which represent either those [[Space Marine Legion#Second Founding|Loyalist]] forces who fight in the name of the [[Emperor]], or the [[Chaos Space Marine#Traitor Legions|Traitors]] who have chosen to side with Warmaster [[Horus]].{{Fn|2b}}

From careful recreation of the detailed panoply and heraldry of the Legiones Astartes, to the organisation of exciting scenarios and campaigns for groups of like-minded friends or the creation of dioramas displaying iconic moments, the hobby provides a wealth of options.{{Fn|2a}}

Set roughly ten thousand years before the time of Warhammer 40,000, the game system takes place during with the events of the tumultuous [[Horus Heresy]] and includes weapons and characters such as [[Primarch]]s which existed during that time.{{Fn|1}}

The vast armies of the [[Imperium]] are sundered by the betrayal of the [[Warmaster Horus]], who seeks to overthrow the [[Emperor]] and forge his own dark empire. Under the banner of Imperial [[Primarch#List of Primarchs|Loyalists or the Traitors]] of Horus, the [[Space Marine Legions]], [[Mechanicum Taghmata]] and endless hosts of the [[Solar Auxilia|Imperial Army]] clash in a war that will reshape the galaxy.{{Fn|2a}}

*;1st Edition (2012)

::First played with the [[Warhammer 40,000 6th Edition Rulebook|6th]]{{Fn|5a}} and then [[Warhammer 40,000 7th Edition Rulebook|7th]] editions ruleset from [[Warhammer 40000]], it received its [[Horus Heresy: Age Of Darkness Rulebook|own rulebook in 2017]].{{Fn|2b}}

::The [[Horus Heresy: Age Of Darkness 2nd Edition Rulebook|2nd Edition]] of The Horus Heresy was released in 2022, alongside a new box set: [[The Horus Heresy: Age of Darkness]]. This edition refreshes the rules, while injecting new decision-making into the mix. It is supplemented by new [[Horus Heresy: Age Of Darkness 2nd Edition Rulebook#Supplements|Army Books]].{{Fn|3}}

*[[Miniatures (Horus Heresy Legions)]]

**[[Miniatures (Loyalists)]]

*[[Miniatures:Mechanicum|Miniatures (Mechanicum)]]

* {{Endn|1}} : [http://www.forgeworld.co.uk/The_Horus_Heresy/Horus_Heresy_Books Forge World]

* {{Endn|2}} : [[Horus Heresy: Age Of Darkness 1st Edition Rulebook]]