not sure i'd call manhunt a horror game exactly.
there's also a bunch of visual novels that fit this bill. Higurashi being the cleanest one (as in, no H), and one of the biggest of the genre as well, certainly more than some other games on that list. i also assume you'll mention Fatal Frame 2 in passing of 1 because it's generally considered the scariest one.
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The future must protect the clone's past.
"Maybe it's a tentacle, molesting the planet itself. - Aschen Brodel.