Thats only when I thought I've done most of it in the most populated and NPC-filled areas, I was happy I found this as a check-list to know did I missed much in fact or not
Interesting thing is oven in the Chaos's house. Is it riddle not easy solved? It it only just what it is? Blood pool in Sharp Teeth... Thats things like those one would like to discover by himself or with a friends, as much as Hilltop statues riddles.