What's the truth of the world? The protagonists in both the series seek the answer to this question. The worldbuilding in these 2 series is unimaginably excellent. These 2 series take place in a world full of secrets and lies. They focus on supernatural mysteries and are deep and highly logical. There are lot of revelations that might leave you shocked. They share a similar eerie and dark atmosphere. It's interesting to see characters make deductions and strategies. SNK s3 is waaay better than its prequels. Music is exceptionally excellent. Art and background scenery is awesome. There will be interesting theories and philosophies.
These 2 are sequels to a series which have developed a deep mystery, but did not reveal a lot of answers. Finally, the answers are revealed (even if bot all in SNK s3 but a lot more than its prequels). There are too many secrets. I found them totally mind-blowing. It's interesting to see the characters make deductions and strategies. You might come to know that there were hints in the prequel but you missed them or things you thought to be less important turn out to be a key to solving the mystery.