Woah. This game takes me back to the first time I played Adventure; I was so terrified when I reached the dark section that I rushed out immediately and refused to explore further until the next day. This game has a similar feel: you don't want to progress for fear of what you might find, but feel compelled to progress nonetheless.
The writing really makes the game; crisp, succinct, vivid and chilling. An interesting touch was the total lack of compass directions; you navigate with commands such as left, right, forward etc. This defiance of genre traditions actually works surprisingly well, adding to the feeling of realism.
The structure of the game is not so much defined by puzzles as by learn-by-dying. Save often and expect to die often. In fact, if you play from a walkthrough and never die, you'll miss some of the best writing in the game. If you really really really need a walkthrough, I'd recommend saving often and trying different ways to die anyway.
Overall, in terms of craft and writing, this is an excellent game. I'm rating it only four stars, however, because of its small scope. Regardless of the small size, Hunter, in Darkness is definitely worth a play.