What makes a nightmare come true story so terrifying?

There are several factors. First, the use of found - footage and documentary - like elements gives it an air of authenticity. Second, the disturbing events that unfold, like the strange disappearances and the menacing presence in the Roanoke house. The idea that something like this could potentially happen in real life, based on the show's claim of being a true story, really amps up the terror.

It could be the element of the unknown. When things happen that can't be easily explained, it's very scary.

One thing that makes a nightmare short story terrifying is the sense of helplessness. The protagonists usually find themselves in situations where they have little control. For instance, in 'The Monkey's Paw', the family is at the mercy of the paw's wishes and the consequences that come with them. The unexpected twists and turns, like in 'The Black Cat' where the narrator's actions spiral out of control, also contribute to the nightmarish quality.

The fact that it's based on real events makes it scarier. You know something similar could happen in real life.

The real - life aspect. These stories often claim to be based on true events, which makes them scarier. We know that things like haunted houses and cursed objects can potentially exist in our world.

The unknown elements in nightmare scary stories make them terrifying. For example, in stories about haunted places, we don't know exactly what the entity is that's causing the hauntings. Is it a ghost? A demon? This uncertainty plays on our fears.

The realism in Mr Nightmare's stories makes them terrifying. These are not fictional horror tales but things that actually happened to people. For example, the way normal people are thrown into these strange and often dangerous situations that defy explanation.

The atmosphere. It's often set in dark and isolated places, which instantly creates a sense of dread. The unknown lurking in those shadows makes you constantly on edge.

The unknown. In real nightmare short stories, often the scariest part is not knowing what's going to happen next. Like in a story where a character is in a pitch - black room and hears strange noises but has no idea what's making them.

It could be the fact that it was a real event. Knowing that people actually faced this plague, with all its consequences like the spread of disease, the breakdown of communities, and the helplessness in the face of it, makes it terrifying. It might also show the ineffectiveness of initial responses, which added to the horror.