Its impossible to play something so harshly tuned without knowledge of the game first. Remember - you know where and what is located, but we have to explore. Each step and turn counts. Can't look around (drains sanity as much as step does), can't take unoptimized route. Most of sanity restorations are hidden behind secret walls. The idea is good, but sanity drain is too much. Either there should be no punishment for turning, so we could look around at least, less drain in general, or more visible sanity restorations there and there to make exploration being not as punishing.
Personally I found 3 runes, a cat, some statue with an eye and a bunch of 'hidden' restore sanity places. I saw door for 3d rune, but sanity drain killed me before I reached it. Also for some reason after death all movements are locked and the only way to go is to restart the game.