I know it's stupid but the original Bridge Curse: Road to Salvation. Which, incidentally, is going to be my one spooky game this year... I still haven't been able to bring myself to finish it, so maybe it'll happen this year.
Has a video game ever truly 𝙎𝘾𝘼𝙍𝙀𝘿 you so much that you almost felt too creeped out to continue playing it?