Stealth Gaming in a Gothic Steampunk World

** The Dark Mod wins PC Gamer's 2013 Mod of the Year award! **

“It’s a tremendous achievement – a detailed tribute to the Thief series…. Projects like The Dark Mod are a way for those fans to say “if you won’t make it, we will” – to deftly lift what was good and meaningful about the games that inspired us years ago and run away with it.”
PC Gamer

“this is splendid….it’s basically Thief…but in Doom 3.”
–Rock, Paper, Shotgun

THE DARK MOD was once total conversion of Doom 3, and now is a STANDALONE GAME with the release of TDM 2.0!

A dark and moody stealth game, inspired by the "Thief" series by Looking Glass Studios, The Dark Mod includes creative new gameplay features, dozens of unique AI, and a complete set of custom art assets, allowing players and mappers alike to enjoy missions in a gothic steampunk universe. When you play The Dark Mod, you feel like you’re playing a gothic stealth game…there’s nothing left that’s recognizable from Doom 3.

This game is first and foremost a toolkit, allowing fans and team-members to create their own stealth missions in a gothic steampunk environment. But there are already over 100 full missions for download, including some small campaigns, so it certainly feels like a game. The only difference is that you have to choose which missions to install and play.


The Dark Mod world can be viewed as an alternate version of our own. It is a mixture of several historical periods, with architecture ranging from medieval castles to Victorian mansions. In this world, steam and clockwork technology were discovered much earlier in history, allowing for odd inventions and industrial warehouses to exist side-by-side with Gothic cathedrals and sword-wielding city watch.

Return to the City V2 (Re-Release) Part 2


We also maintain our own mission editor, called Dark Radiant. It is an updated version of GTKRadiant, and has a lot new features (Python scripting support, many bug-fixes, new Particle preview, Texture Tool etc.) and comes with a number of Dark Mod related plug-ins like an Objectives or Conversation editor.

Example Editing:

Try it yourself!



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Broken Glass Studios are very pleased to announce

the release of The Dark Mod 2.05!

TDM 2.05 Article

This update includes literally hundreds of new high-quality models & other assets, along with an update to the editor that will change the way TDM missions look going forward.

Please see the latest official trailer above for a quick teaser.

New Modular Models

Springheel has created over two hundred modular models that can be combined to create multiple types of environments. Tavern interiors, city streets, industrial warehouses and more. By placing modules together, high fidelity scenes can be created quicker and more easily than ever before.

2.05 article 2

New Official Mission

Many of the above new assets are showcased in a new "introductory mission"

that is included in this update.

This mission is the first of a three mission story which serves as our

official introduction to TDM's game-play and setting.

TDM 2.05 Article

Better Performance

You should notice an increase in performance speed in TDM 2.05,

thanks to rendering improvements made by duzenko and nbohr1more.

The main improvement to TDM 2.05's performance is Lightgem Rendering.

To accomplish the Lightgem functionality in The Dark Mod we originally had to dig around in the game SDK for places where we could communicate with the renderer. This was primarily done via the in-game camera systems and tricks with piping screenshot files to a RAM workspace.

(some background info)

The way the system works is:
1) If it is time to create a Lightgem image, initialize a new "View" (aka camera)
2) The player model, held objects, and other non-essential objects are hidden
3) The player model is replaced with a low-poly representation (octahedron)

(Octahedron with eyes representing cameras)
TDM 2.05 Article

4) The camera is positioned facing down at the octahedron (below)
TDM 2.05 Article

5) The scene is rendered and captured to memory

6) The camera is positioned facing upward looking at the bottom of the octahedron (below)
TDM 2.05 Article

7) The scene is rendered and the image is captured to memory

8) The images are combined and then analyzed for the brightest values
9) A final light level value is return to the game code to be adjusted further by other visibility factors

With the above screenshots, the process certainly looks wasteful but those are only hand-made representations I created by spawning the octahedron model in-game. The real Lightgem render would crop away everything but the boundaries of the octahedron leaving you with a square made of 4 shaded triangles.

Still, id Tech 4 (Doom 3 engine) is very nervous about throwing away scene data during a render. If there is anything that could cast a shadow or show-up in a mirror, transparency, or postprocess the engine will tend to do a substantial amount of setup before deciding to discard the data just before sending it to the video card for render (or will actually render the invisible stuff if all the culling heuristics fail).

( Edit: Hah! It's even worse than I thought. According to Serpentine (one of the old core coders) the lightgem camera is actually inside the octahedron (an optimization I was planning on doing). This means that the visibility culling heuristics are really falling down or else these latest changes wouldn't have been so effective. )

In TDM 2.03, SteveL was struggling with the particle system and (as part of his cleanup work) he ensured that particles no longer make-up the above workload. To everyone's surprise, this was a pretty significant performance boost to scenes with lots of particles.

In 2.04 SteveL added the ability to omit Lights from the Lightgem calculation so that mappers could place decorative "bounce lights" around their maps without having to struggle against the Lightgem (because the brightest part of those lights was typically floating in mid-air and invisible to the player 'till they stepped into it).

This work laid the groundwork for the 2.05 Lightgem changes.

In 2.05 the octahedron was given a new material type "islightgemsurf" to allow the following change:

Skip all surfaces that can't create shadows except "islightgemsurf"

This, along with skipping all lights that the player isn't "inside of" drastically cut the amount of work for the Lightgem render phase.

But we were not done yet!

A new coder "Duzenko" (and veteran of the Russian "Darkfate" Thief community) arrived to complain about the cost of the Lightgem render prior to the above changes.

Parallel to the above development, he looked into another expensive aspect of the Lightgem:

"Pixel reading".

Even though our Lightgem image capture was given a superhighway to native memory space in 1.08 the process of feeding the render to RAM was still pretty slow. Duzenko studied the problem and found that an ancient OpenGL 2.1 feature called Pixel Packed Buffers would do a better job than our very legacy OpenGL code. This lead to some drastic performance improvements in fillrate heavy scenes like the cave in "No Honor Among Thieves" mission 1.

A little tangent on tweaking...

Part of the genesis of the above Lightgem optimization was my own pet project to improve our documentation on performance tweaks and cvars:

In the forums, there had been at least a few confusing\inconclusive discussions about one tweak that seemed to offer the biggest performance boost but came with some pretty bad caveats "tdm_lg_interleave"...


This console variable allows you to specify how often to capture Lightgem renders. By default, this is done in every frame. Users were finding that setting it to 2 or 3 would nearly double FPS is some scenes but it was also causing terrible stutter, especially where the average FPS was below 30. It occurred to me that automatically enabling or disabling the larger skip values depending on your FPS was the ideal solution, so I created a new cvar tdm_lg_interleave_min that allows you to say "if my FPS is below X then set tdm_lg_interleave to 1 to avoid stutter". The default value is 40 (FPS).


This console variable was created shortly after tdm_lg_interleave at the dawn of TDM to address the same stutter concern above. It was posited that the biggest problem with tdm_lg_interleave was that the frame load was so uneven with the huge wallop of frame cost during the full Lightgem scenes. One of the developers suggested calculating only the top or bottom of the Lightgem capture per pass so that the render load would be much closer to the non-Lightgem passes. This worked great but was never enabled by default in The Dark Mod because it caused particle effects to flicker. With SteveL's exclusion of particles in 2.03 the flicker is gone so this feature has been enabled by default. Further, it can be paired with tdm_lg_interleave so that the interleave frames calculate half the scene every x number of frames.

With the above knowledge, feel free to try setting tdm_lg_interleave to higher values now. I have been playing with tdm_lg_interleave 3 but I've tested it as high as 8 without seeing any stutter or anomalies. For most missions, I can set tdm_lg_interleave_min to 1 along with tdm_lg_interleave 3 and gain FPS (even at sub 30FPS areas ) with no consequence for frame stutter but Penny Dreadful 3 required me to increase the min to 50 to avoid stutter at the start area. Your mileage may vary.


The old image_downSize cvar settings that allow you to shrink and degrade texture quality to reduce video RAM consumption (and bandwidth consumption), no longer cause menus and GUI's (maps, signs, etc) to become blurry.

If you have limited video memory, try reducing these settings now that they no longer affect play-ability.

New AI

Grayman has added a working fire elemental to our list of available. AI opponents that will no doubt appear in future missions.

Cubemap Lights

Shortly before the horrific death of the legendary forums (due to a Spammer invasion), Sikkpin (the author of Sikkmod) went on a tangent and solved a longstanding riddle about Doom 3 lighting...

Doom 3's flexible material system allows you all sorts of image manipulation options to feed into what lights project on surfaces. You can have anything as simple as a flat circle to a stained-glass window pattern or even a movie projector film. During the wild experiments in the early Doom 3 mod scene, some folks found that lights could accept "Cubemaps" (six images representing all six degrees of projection) but the result was completely wrong. This was because the sampler was just taking data from the final 2D transform of the image and using it as the projection image. Sikkpin worked around this problem by creating new vertex projection matrices in the vertex shader and changed the sampler behavior in the pixel shader.

He also did a little trick to tell the shader how to behave if the light entity was set as Omni or Projected and finally he implemented an ambient component based on Half Life 2's ambient cubemap system.

All packed into one shader, phew!

The benefit of cubemap lights is that you can more realistically represent what comes out of complex light sources such as our desk lamps.

Crude example (Before):
2.05 article 3

Notice how the floor has the same projection image as the ceiling. This is due to the 1D + 2D image setup for normal Doom 3 lights.

Crude Example (After)
2.05 article 3

Now only the ceiling has the pattern so the behavior is more realistic. Further the image is contorted spherically the way a real light projects such an image.

(Folks who regularly use Unity "Cookie Lights" should be well aware of how cubemap based light sources work.) You can also project 6 different lights for the price of rendering one light (as long as you are willing to accept that these lights must all be oriented in a cube pattern around one light_center)

HL2 in The Dark Mod
2.05 article 3

Now mission authors can use the Skybox or other cubemap images to create ambient lighting and environment reflections similar to HL2's ambient cubemap system.

Even though these features were created before Doom 3 went Open Source, we could not integrate them because we would've had to replace all existing lights with Cubemap lights.

Thanks to Rebb's work to setup a dedicated Ambient light shader pass, I was able to add branches to the renderer so the above shaders can occupy the same scene as the standard Doom 3 lights.

Right now we only have a few cube materials so if you know of any resources to generate Cubemap \ Cookie light textures or know of open licensed asset collections, please let us know.

Thank you Sikkpin (wherever you are)!


Setting com_fixedTic 1 will now allow The Dark Mod to render over 60FPS without causing everything to speed-up. Duzenko ported some of the BFG code around this functionality to reduce the CPU impact of frame sync (for lowend users) but this feature can be useful to folks experimenting with Virtual Reality HMD.

I will note that there are a few quirks.

1) FPS above 200 can paradoxically cause the game to run in slow-motion or cause other strange pacing issues

2) The breath potion exhausts more quickly the higher the FPS you have

To prevent FPS from going over 144 or 90 you can create an autoexec.cfg file and place seta r_displayRefresh "90" in it to force your screen refresh then either use r_swapinterval 1 (enable vsync in-game) or enable vsync via your driver. Setting r_displayRefresh can also smooth out frame behavior on digital displays (HDMI, DVI, DisplayPort) where refresh detection can be problematic for Doom 3 so it's a good idea to set this via an autoexec.cfg regardless.

Bug fixes

Other changes include a fix to stop sleepers from falling through the floor, new beggar entities, new combination safe entities, and fixes to stop the player or AI from getting trapped by moving elevators. A more detailed list of changes can be seen in the change log and on the Wiki

Special thanks go to Bob Necro for his large texture collection contributions, Airship Ballet for prefab containers and paintings, Epifire for Steampunk models, Spooks for his example cubicLight textures, Outsider One for his Turkish menu translation, and Hamlet & Nightstalker who worked to resolve Linux compile issues and distribution problems.

Darkradiant updated

Greebo has also just release the latest version of Dark Radiant 2.2.1

Of significance in this version, you can now scale models in the editor and save the scaled model as a new model. This adds substantial flexibility to the modular model based approach described by Springheel above.


Also, support for grouping selected items for manipulation has been added. You can group huge collections of models and rotate or translate the entire collection at once, saving substantial amounts of time during mission creation.

Additional info

You can update your copy of TDM by running tdm_update.exe and as always, older saved games will be incompatible with TDM 2.05, so be sure to complete any missions you're in the middle of before updating!

The Dark Mod on GREENLIGHT!

greenlight tdm

At the (unexpected) twilight of the GreenLight offering, The Dark Mod team has finally gone though all the legal, financial, and social issues to enter into the GreenLight process.

Hopefully we will make it onto Steam before this process is ended. Although votes aren't the only metric to qualify for GreenLight approval, I feel that I must mention (boast?) that we were in the Top 10 ranking just recently!

Please visit our GreenLight page and cast your vote.

Down by the Riverside

Down by the Riverside

News 5 comments

Down by the Riverside, Dragofer's emergence! Dragofer has outdone himself with a new mini-campaign for The Dark Mod.

The Dark Mod 2.04 is out!

The Dark Mod 2.04 is out!

News 9 comments

The long road to the 2.04 release has ended. 2.04 is the culmination of over a year's worth of bug fixes and feature additions. We have cured a number...

The Voice of Reason: A Goldwell Interview

The Voice of Reason: A Goldwell Interview

News 4 comments

With his 4th mission mission under foot, Goldwell has proven to be a pillar of TDM quality.

Crucible of Omens: Behind Closed Doors

Crucible of Omens: Behind Closed Doors

News 8 comments

The prologue mission for the Crucible of Omens campaign has finally arrived!

Add file RSS Files
The Dark Mod 2.04-2.05 Update Package (Windows)

The Dark Mod 2.04-2.05 Update Package (Windows)

Patch 4 comments

A patch to convert a TDM 2.04 install to 2.05. You may use this along with the other patches here at Moddb to go from the 2.0 Standalone version to 2.05.

The Dark Mod GUI Installer (Windows)

The Dark Mod GUI Installer (Windows)

Installer Tool

Freyk's new GUI installer for The Dark Mod (Windows). This tool simplifies the setup for users who fight with Window folder permissions (etc) when trying...

[Beta] The Dark Mod 2.05 Native OSX binaries

[Beta] The Dark Mod 2.05 Native OSX binaries

Patch 1 comment

These files allow MacOS or OSX users to run The Dark Mod 2.05 natively rather than via Play-On-Mac.

The Dark Mod 1.06-1.07 Update Package (Windows)

The Dark Mod 1.06-1.07 Update Package (Windows)


A patch to update TDM 1.06 to 1.07. The last TDM version to use the Doom 3 SDK rather than the GPL Doom 3 source release. (Compatible with some missions...

The Dark Mod 2.03-2.04 Update Package (Windows)

The Dark Mod 2.03-2.04 Update Package (Windows)

Patch 3 comments

This is a standalone archive release of The Dark Mod's 2.01 update, to be applied to an installation of The Dark Mod 2.0.

The Dark Mod 2.0-2.01 Update Package (Windows)

The Dark Mod 2.0-2.01 Update Package (Windows)

Patch 1 comment

This is a standalone archive release of The Dark Mod's 2.01 update, to be applied to an installation of The Dark Mod 2.0.

Comments  (0 - 10 of 547)

when is this going to be on steam? :'O

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release date when?

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I just installed TDM and some of the downloadable missions...this is just amazing. Ive played all of the thief series except thief 4. So good to see fans doing things like this! Keep up the good work!

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Still trucking along. Good to see this game getting lots of attention after so many years. Voted.

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Is release date on steam?

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I remember seeing that somebody from the team was feeling down about the mod's popularity. I never posted anything on it's page, but I did play about 10 of the fan missions, and this is one of the few mods across all the games I played that blew me away, in regards to the saying "if AAA won't do it, fans will", or some such, where modern sequels are nothing like the originals. God bless the fans, much love <3

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I've never played this but it looks interesting though I'm a little confused on what I'm supposed to download

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Is there a planned Steam release?

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Good job!

Hey, Can you add release date to maps in level choice menu?
I'd like to play through first to last maps created for The Dark Mod. Beyond this, seems like a good idea to include.

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nbohr1more Creator

Not a bad idea.

Until someone gets around to redesigning the GUI, try our wiki for a quick reference:

Reply Good karma+1 vote
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Ratings closed.

Highest Rated (11 agree) 10/10

Great mod, must play for all thief fans. Contains great, userfriendly editor (To tell the truth, this mod is mainly the editor, and fans are making FMsú and a lot of super missions. Try it and you will be surprised.

Nov 6 2010 by PPoe

Single Player

Latest tweets from @thedarkmod

Anouncing, The Crucible of Omens:

Dec 18 2011

Thief: Turning Doom Into Thief - @Kotaku

Dec 12 2011

Help The Dark Mod win the @moddb #moty 2011 Mod of the Year: you must have a moddb account for the vote to count.

Dec 2 2011

The Dark Mod v1.07 is out! via @ModDB

Nov 29 2011

Firing up TDM 1.07 for some testing this weekend! Some great improvements to the AI in this release!

Nov 10 2011

1.07 is on the way.

Nov 8 2011

1.06 has been released! Run tdm_update to get it now. :)

Jun 19 2011

Gearing up for the next update. Firing up 1.06 for some internal testing tonight! :)

Jun 7 2011

Interesting advances within the bowels of The Dark Mod forums. Stay tuned, exciting developments are well underway.

Apr 21 2011

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