The classical instruments in this are well-done but take away from the pure horror aspect and make this more suspense than anything. I can imagine being chased by a boulder, a guy in a car, or maybe zombies in the daytime, but probably not something that would be seen as terrifying on its own.
The driving synth in the background makes for a good substitute for percussion, but gets really repetitive. Even in parts that utilize it less you still hear it toned down.