This was a very fun game to play, both alone and with my siblings. First-person, stationary free-look perspective. A good trigger-based day and night cycle to make you feel the game progress and the story advance at an appropriate pace. And a bunch of unique game mechanics that, against all odds, worked wonderfully. Especially the clue system, which made reading documents more engaging, while helping you keep track of what was relevant. And if you weren't sure where some of the pieces fit, you could try to relate them to others through the "think" mechanic, which would let you try to combine clues that you felt were connected and, if you were right, obtain a new clue from the process. Very lovecraftian feeling beginning to end, in what's otherwise and above all a fun detective game.
It has a free-roam first-person sequel, more in the Amnesia or Scratches fashion, which seemd pretty OK as well. GOG currently only has a third game by this developer (not sure if there's any link to the Darkness Withing franchise), Conarium, which I have yet to play. But it would be great to have these interesting games added to the catalogue - I would certainly grab them on the spot!