If you want an ACTUAL horror-survival-adventure game (on mac), I would recommend:
The Dark Eye — based on Edgar Allan Poe stories, fair graphics, top of all the lists I’ve looked up in the past on the subject. Truly great.
I Have No Mouth and I Must Scream — HOLY SH*T YOUR PANTS SCARY
The Path — the most twisted and sickening take on Little Red Riding Hood you’ll EVER encounter. Great graphics and sound, came out early 2009
Downfall — someone has made a mac port for this. also a 2009 game… ew.
THE LOST CROWN: A GHOST HUNTING ADVENTURE — If you can find this for mac, GET IT
The first 3 you can definitely get for mac, last 2 are less likely.