Well, they are very concise. For example, 'I saw a figure in the corner. It disappeared when I blinked.' They quickly set a spooky mood in just two sentences. There's no need for a long build - up, and they often leave a lot to the imagination. The first sentence usually creates a normal or slightly strange situation, like 'The phone rang at midnight.' And the second sentence takes it to a terrifying level, such as 'But no one was on the other end.' This brevity makes them very effective in delivering a quick horror fix.
The feeling of being alone and hunted. When you're hiding in a horror - themed hide and seek, you know there's something out there looking for you, and that sense of isolation makes it scarier.
One 'hide and seek horror story' is about a group of kids playing in an old, abandoned house. When it was time to seek, the seeker found that one of the hiders had disappeared. Later, they heard strange noises from the attic and when they went up, they saw a figure that looked like the missing kid but with a distorted face. It was really spooky.
Another really scary one could be 'My phone rang at 3 am. The caller ID said it was me.' It plays on the idea of the self being something other or unknown, and calls at that time are always spooky.
They often involve being trapped, like in the riddle of the room with no exit. Trapped situations are inherently scary. It makes you feel the helplessness of the character in the riddle.
Well, there was this 'hide and seek horror story' where a family was staying in a haunted inn. The kids decided to play hide and seek. One child hid under a bed. While under there, she saw a pair of feet walking around the room slowly. But when she looked up, there was no one there. The feet kept walking and she could feel a cold presence. It made her realize that the inn had some truly terrifying secrets.