From the moment I saw the title page, I was hooked. I've played through this game numerous times, and I've yet to tire of it.
The dream-like feeling of it all is pulled off perfectly. With the sort of style it is easy to come across sounding pretentious and overly-complicated, but the author here manages to make it all feel natural.
Overall, it's a well constructed, interesting, and artistic game. I highly recommend it to anyone, even those who don't like IF.
This is the game that got me into interactive fiction. The writing is wonderful, the atmosphere is perfect, the setting is carefully constructed, and the story is captivating and frightening.
One thing to note -- something I certainly wasn't expecting when I first started playing -- is that Anchorhead is hard, as well as almost massive compared to most IF games I've played since. Those aren't necessarily bad things, though, and in fact I'd say they made the game much better.
Bottom line is, if you like Lovecraftian horror, then you'll love this game.