The Horus Heresy: Betrayal at Calth is a turn-based combat epic set during the origin era of Warhammer 40k. Play on either PC or VR, as the game will detect your platform choice. Take command of Ultramarines as they battle against their traitorous brethren, the Word Bearers. VR HEADSET NOT REQUIRED TO PLAY.
All Reviews:
Mostly Positive (38) - 78% of the 38 user reviews for this game are positive.
Release Date:
Feb 27, 2018

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Early Access Game

Get instant access and start playing; get involved with this game as it develops.

Note: This Early Access game is not complete and may or may not change further. If you are not excited to play this game in its current state, then you should wait to see if the game progresses further in development. Learn more

What the developers have to say:

Why Early Access?

“We believe The Horus Heresy: Betrayal at Calth is a perfect candidate for Early Access. It is essentially a turn based tabletop game playable in VR and non-VR PC. As this is such a unique title, we would like as much feedback as possible from the Warhammer community before locking down a full release.”

Approximately how long will this game be in Early Access?

“The Horus Heresy: Betrayal at Calth will be in early access for approx 6-8 months. When the final single player Act is completed, it will be ready for a full release.”

How is the full version planned to differ from the Early Access version?

“The initial Early Access release will not include the full game. Over the course of the Early Access release, we will make frequent updates until all aspects of the full game are represented.

1) SINGLE PLAYER - The full version of the game will include a 5 Act single player story mode. When the Early Release launches, it will only include Act 1. The additional acts will be added periodically during Early Release similar to an "episodic" story game.

2) SKIRMISH - Single player "Skirmish" mode will be added so players can play multiplayer maps against the AI.

3) ADDITIONAL CONTENT- New playable units, weapons, maps and costumes will be added during Early Access.”

What is the current state of the Early Access version?

“The game currently has Act 1 of the single player mode and 5 multiplayer maps. Music, Animation, Art, Gameplay is final for this content.”

Will the game be priced differently during and after Early Access?

“Early Access will be listed at a reduced price.”

How are you planning on involving the Community in your development process?

“We plan on addressing notes and suggestions through the Steam community pages as well as on our Facebook and other social media pages. We want to make the best game possible by listening to our Early Access community.”
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Notice: Requires one of the following virtual reality headsets: HTC Vive or Oculus Rift. See the VR Support section for more info.

Buy The Horus Heresy: Betrayal At Calth - Early Access


Recent updates View all (16)

October 23

Act 3 Patch

Main Fixes in this patch include:

  • Fixed 3-1 Lighting
  • Fixed Moritat/Orestes death on assault game lock up
  • Fixed pink textures in M1 and M3
  • Fixed no units available in army builder
  • Fixed Player/Enemy Reinforcements text on tactical map
  • Fixed 3-2 Lighting
  • 3-2 Removed walkable area that was over a pit
  • Fixed continue button position in VR
  • Fixed drop downs not working in the graphics options on the main menu in VR

    Known post patch issues:

  • Army Builder is not fully functional in VR
  • Acastus may have model glitches

    As always please post any issues you come across into bug-reports. Thanks everyone!
2 comments Read more

October 17


War has raged under Calth long after the actions on the surface, protracted conflicts to slay entrenched Word Bearers throughout the planets depths carry on. It has been 4 years since Squad Acastus secured a teleportarium and routed the Word Bearers from their librarium outpost.

Our story picks up with a Legion Moritat, Orestes, attempting to rescue Calth Defence Forces from being sacrificed by Word Bearer cultists.

What’s New with Betrayal at Calth?
Enjoy the planet Calth on our beautiful new title screen!
ACT 3 is by far the biggest release so far with 6 new single player levels and 4 new unit types.
A number of UI updates have arrived, as always they are part of an ongoing process of updates. New Marine models are in the process of being added, they are in singleplayer at the moment and will be coming to multiplayer and other game modes as future updates roll out. For VR users, gameplay should be more stable, but we still have a lot of future changes coming up for those users specifically. Some sound fx have been updated.


  • Legion Moritat: A highly mobile and deadly unit, capable of hit and run tactics and devastating damage to smaller isolated targets.

  • Calth Defense Forces: Drawn from the wider Ultramar Auxilia, Calth’s mortal defenders pack a punch with their numbers. Skilled at regrouping, and reinforcing one another and using cutting edge las weaponry, these troops provide valuable assistance to the Ultramarines.

  • Legion Apothecary: Practiced in both combat and healing, they can turn the tide by providing healing buffs to local forces. At close range an apothecary unit can provide deadly melee support to their brethren.

  • Word Bearer Cult Troops: Mortal soldiers of the Word Bearers. Wielding traditional solid munition weapons and a ferocious devotion to their masters, these traitor forces can use their numbers to protect allied astartes, and to overwhelm careless opponents.


    This act will be in beta at time of release. You may notice some bugs and or visual errors!

    Some common known issues at time of beta release include:

  • Multiplayer will have a number of hiccups and possible loading glitches, but is playable.

  • Story dialogue plates in act 1 are not up to date, and not currently implemented in acts 2 and 3.

  • Mission 3_1 will rarely freeze after a few rounds, this occasionally can be resolved by waiting a moment but otherwise will require an application restart.

  • Some Units do not have voice lines and or final voice line at this time, these will be patched in as they are ready, we will release patch notes for this.

  • Some weapon fx may sync off or trigger at odd moments.

  • Armor on marines may sometimes not appear correctly, two known possibilities include marine heads becoming invisible at large distances, and shoulder pauldrons becoming invisible when certain weapons are equipped.

  • Many gunfire animations can still fire in wild directions or through objects. This will be addressed in a future patch.

    As always, if you encounter any concerning issues please send a log or description of the issue to:
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“40k board game adaptation The Horus Heresy: Betrayal At Calth stomps into early access FOR THE EMPEROR!”
Rock Paper Shotgun

“Lead the Ultramarines into battle on what they’re calling a human-scaled battlefield…and, if you don’t know why that’s incredible, check out the video. Holy cow.”
Bell of Lost Souls

“I like the camera view. I like the way it provides an opportunity for the player to survey all the cool stuff. And the maps are actually really well-designed too. If you look at the environment, it's puuuuuuuurty!”


Here are the requirements for VR players on the HTC Vive or Oculus Touch:


OS: Windows 8
Processor: Intel i5-4590 or greater / AMD FX 8350 or greater
Memory: 9 GB RAM
Graphics: NVIDIA GeForce GTX 970 / AMD R9 390
DirectX: Version 11
Storage: 30 GB available space


Graphics: NVIDIA GeForce GTX 980 / AMD R9 390X
DirectX: Version 11
Storage: 40 GB available space


About This Game

Immerse yourself in the Horus Heresy the epic origin story
of the Warhammer 40,000 Universe!

The first shots have been fired in the conflict that will change the future of mankind. Brother Legions of Space Marines taking arms against one another. The noble Ultramarines are betrayed on Calth by the zealous Word Bearers bent on tearing down the Imperium. A dark ritual ignites the system’s star, sending both Legions underground to battle for their honor, their belief, the fate of the Imperium, or just to survive.

The Horus Heresy: Betrayal at Calth is a game of turn-based skirmishes between the genetically altered warriors of the 31st Millennium, The Adeptus Astartes. In the campaign, players control units of Space Marine Legionnaires, guiding them through the underground arcologies of Calth. Fight alongside units of Ultramarines ranging from basic Legionnaires, Veterans, and Sergeants, to elite units of Terminators, and the most venerable Contemptor Dreadnought. Dispatch the foul heretics of the Word Bearers using a mighty arsenal, from the ranged accuracy of Bolters, Plasma Guns, Flamers, and Rocket Launchers, to the close combat might of Chainswords, Power Fists, and Lightning Claws.

The Horus Heresy: Betrayal at Calth also includes several Multiplayer maps allowing players to fight as Ultramarines or Word Bearers in either objective based missions or deathmatch. Bring the full arsenal of your chosen Legion to bear against friends with private matches or against opponents across the world with built in matchmaking. Multiplayer mode is available to both PC and VR players, allowing both formats to play against one another.



  • Original Horus Heresy Narrative: Set in the 31st Millennium on the planet of Calth, Magos Ohmnal Sarc commands a unit of Ultramarines. When he discovers corrupted data in the data stream, Sarc is confronted with a faction of aggressive Word Bearers and a devastating plot of corruption within the Imperium that introduces untold threats and schemes against the Emperor. The original story was written by Black Library author Rob Sanders.

  • A Living Battlefield: While players decide on their next action or wait on their opponent, the world around them continues to animate and fight.

  • Multiplayer Skirmish Mode: Players can choose between the Ultramarines and Word Bearers factions. Units include Legionaries, Veteran Legionaries, Sergeants and a cast of characters armed with everything from bolters to melta guns to assault cannons. More character classes will be added up until the final game release.

  • Cross-Platform Multiplayer Matchmaking: Play on either gaming PC, HTC Vive or Oculus Touch. As a turn-based game, PC verses VR provides no gameplay advantages, only differing user experiences of the world.

Play In VR

  • VR Mode: The “human-scale” view of Space Marine combat gives the player the feeling of being on the battlefield in a world first VR game set in the Warhammer 40,000 universe.

Coming During Early Access

  • Single-Player Campaign: 24 combat scenarios exploring the conflict between two factions of Space Marines, divided into 5 Acts. The story progresses linearly and each level presents unique challenges intertwined with the drama of the narrative.

  • More Unit Types: Terminators, Dreadnoughts and new unit abilities.

  • Single Player Skirmish verse AI: Skirmish against the AI on multi-player maps.

  • More Multiplayer Maps: As each new story act is released new multi-player maps will be released as well.

  • Legionaire Customization: Customize your Ultramarines and Word Bearers with armor and equipment swaps.

  • Maybe a few surprises!

System Requirements

    • Requires a 64-bit processor and operating system
    • OS: Windows 7
    • Processor: Intel® Core™ 2 Duo 3.0Ghz
    • Memory: 5 GB RAM
    • Graphics: NVIDIA GTX 960 1GB | AMD Radeon HD 5770 1GB | Intel HD4000 @720p
    • DirectX: Version 11
    • Storage: 30 GB available space
    • Requires a 64-bit processor and operating system
    • Graphics: NVIDIA GeForce GTX 1060 4GB | AMD Radeon R9 290X 4GB @1080p
    • DirectX: Version 11
    • Storage: 40 GB available space

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