Dragon Head, 6000 Recommendations
6000 was heavily inspired by Dragon Head--both feature pitch black darkness as a central theme, and explore ideas of fear. Dragon Head has a more epic-style narrative than 6000, and explores apocalyptic themes as well. It was also highly acclaimed at the time of release, and well worth it for fans of very well-written horror.
6000 is more focused on straight up terrifying you than Dragon Head, but it is also extremely well written and concise. It has a good balance of frightening moments and a never-ending feeling of dread.