Very cool this one... it reminds me of JRPG games I grew up on, like Golden Sun or Breath of Fire... the atmosphere's there from the start, but it builds nicely along the way too...
It doesn't feel quite as dark to me in audio as the description seems to portray it, more so adventurous, exciting, a quest, a mystery, a journey... not necessarily straight up purgatory!
Love the sound anyhow, it's tense but also pleasantly atmospheric. :) I think the little whistle sounds contribute to that impression too...
-cd-