The brevity. They leave a lot to the imagination. For example, in 'The phone rang in the empty house', we don't know who's calling or what will happen. It's the unknown that scares us.
Most of these short stories play on our common fears. Like the fear of the dark, the unknown, and being alone. In stories where someone is in an isolated place and hears strange noises, it taps into our primal fear of the unseen. Also, they often have sudden twists. A story might start normally and then end with a really creepy revelation like seeing a ghostly figure right behind you when you thought you were safe. They use these elements to create a sense of unease and horror in a very short space.
Regarding 'She opened her eyes. Darkness everywhere. Then she realized she was already dead.', it's the sudden realization of a terrible truth. The contrast between thinking you're alive and then finding out you're dead is a huge shock. It plays on our fear of the afterlife, of the unknown state of being dead, and the fact that we may not even be aware of our own death.
Well, these short scary stories often play on common fears. Things like the fear of the dark, the unknown, and being alone. They also use elements that are easy to imagine. For instance, a story about a hand reaching out from under the bed. Everyone can picture their own bed and that sudden, unexpected threat. They don't need a lot of description because our minds fill in the blanks with our worst nightmares. Another factor is the element of surprise. In a short story, it can be as simple as a sudden noise or a strange sight that catches you off - guard.
Atmosphere. A good shortest scary story can quickly set a spooky mood. Using words that imply darkness, isolation or the unknown. Like in the story where a girl is in an old house and hears a whisper. The old house, the slamming door and the lights going out all build a terrifying atmosphere.
Maybe it's the unknown elements in 'the appointment scary stories'. Often, when we don't know what's going to happen next, it creates fear.
The element of truth in these stories makes them scary. When we know that something really happened, it becomes more terrifying. For example, if a story is about a real murder case with some unexplained aspects, like the killer was never found or there were strange circumstances around the crime. It makes us feel that such danger could be lurking around us too.
The fear of the supernatural that these stories play on is what makes them so scary. Since we live in a world where the natural laws seem to govern everything, the idea of a goast that defies these laws is deeply unsettling. It challenges our understanding of reality and makes us feel vulnerable.
Alligators are unpredictable. In stories, they can be lurking quietly in the water or the mud, and suddenly lunge at their prey without warning. Also, their powerful jaws are a big part of what makes them scary. Once they clamp down on something, it's very difficult for their prey to escape.
The unknown elements in Denis scary stories are likely to be very scary. Our minds tend to fill in the blanks with the scariest things we can imagine when we're not given all the details. Also, the atmosphere created, like a gloomy setting or a sense of isolation, can heighten the scariness. If the story is set in a deserted place where no one can hear the characters scream, it adds to the fear factor.
The realism might make them scary. If they are true, it means these events could potentially happen to anyone.
The use of atmosphere. For example, in many stories, it's often a dark and isolated setting like an old abandoned house or a desolate forest. This immediately makes the reader feel uneasy.