THE DARK MOD was once a total conversion of Doom 3, and is now 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.

TheUnbeholden says

10/10 - Agree Disagree

The best mod I've ever played. While it doesn't have the grandness that the Nameless mod has from a long winding campaign, it however comes in a more varied package by allowing you to play fan missions with gameplay that's like a updated version of Thief 1 and 2. The Dark Mod has alot of work done that transforms Doom 3 into Thief. I have no idea how they managed to accomplish this but if they didn't say it was a Doom 3 I would not have known...
The Dark mod is really the best thing to play while waiting for Thief 4. Its alot better then Thief 3 in alot of ways, its environments are larger like back in the good old days of thief 1 & 2 and its got rope arrows.

Its mantling and movement is so fluid its like nothing I've ever seen before. And reading books is in real time instead of pausing the game, which I thought adds to the tension/immersiveness.
Interaction with the environment and items is also really immersing, the way you can rotate items your holding, hold them further from your body, or closer. I have alot of fun just throwing them around, physics on them is just really beautiful to see. Seeing rats scuttering about is also a pleasant surprise.
Lockpicking is interesting to say the least, its always different in every Thief game and this mod is once again different. It require precise timing, attention to hearing (the game provides you with a difficulty setting for it thankfully in case you think its hard).
Voice work is a neat addition, and while the mod could use more lines it has decent voice acting.

...and the recent patch fixes my issues with blackjacking.
All that really remains that seems unfinished is the sword combat. But then again I've never played Thief for that so I guess it doesn't really matter.
It doesn't have 3rd person but I've always thought first person is far more immersive.

Now is better time then ever, especially considering Doom 3 can be gotten for $20 on steam (I got it for $5 on a weekend sale).