I'm in no particular good mood right now and as my mind wanders I ask myself if there ever were pc games that featured an overall dark setting and/or story. As I can not come up with something apart maybe from 'vampire the masquarade - bloodlines' my thesis is that there may not be many games in this category.

Internet... enlighten me! ;)

- Legacy of Kain series
-Manhunt

I Have No Mouth, And I Must Scream.

The characters are the only five surviving members of the human race. They are trapped in the demented world created by a supercomputer named AM with nigh-Godlike powers to alter reality, and a massive hate-on for humans. At the point the game starts, AM has already been torturing them for centuries. Throughout the game, AM proceeds to create a new personalized hell for each one of them, and you must play through each of them. You then have to see how well each character can acquit themselves when confronted with what is essentially a hopeless no-win situation, with no prospects other than eternal damnation and no way to "achieve" anything other than to resist AM's efforts to further dehumanize them.

That dark enough for ya?

the witcher series ... and old school games planescape torment and baldurs gate 2

Fallout 1 is pretty damn dark when it's not busy being goofy. The "bad ending" movies in particular are pretty grim.

And Amnesia, of course, though that's more "spooky" dark than "disturbing" dark.

Manhunt's a nasty, ugly game that left me feeling worse then I did before I played it. Strongly recommended! Avoid the sequel.

Unfortunately, I can't second I Have No Mouth and I Must Scream; it's dark as hell, but I found it obnoxiously obtuse as well.

Really, a lot of horror games are quite dark. Have you played Amensia?

Dark Souls.

And Demon's Souls if you have a PS3.

Eternal Darkness and other games based on the Cthulhu myths.
Maybe the Gabriel Knight games.

Depends on what you mean with dark. I find the blackwell series quite dark, dealing with usual ghost stuff (loss, regret, irreparable mistakes) but also human themes like exploited psychological vulnerability, etc.

I suspect Inquisitor to qualify too, for dark themes.

Pokemon.

Oh, and "The Suffering" as well. Also, The Aliens VS. Predator games are really dark, especially the second one. And don't forget Hitman either :)

The original Postal, Ghostmaster, The Seventh Guest are probably some of the darker games here on GOG.

Also penumbra, and especially penumbra black plague, are as spooky dark as they are disturbing dark.

I've also heard good things about the void, but haven't played it yet.

Spec Ops - The Line

Trust me on this.

Just realized that I forgot Sanitarium and Blood, those are pretty dark games as well.