Gu Shen, a game planner who was laid off, has been able to see "things that shouldn't exist" since he was a child - shadows lurking in the cracks of light. He was diagnosed by doctors as visual hallucinations.
Until he was pulled into the "Abyss Game".
This is a death arena built from the remains of the Great Old Ones and human fears. The reflection of the hospital in the mirror will replace the body, the sound of the silent train attracts extra-dimensional hunters, the whispers of the deep sea transform people into deep divers... Each of the game levels is the embodiment of the nightmare of the Cthulhu mythology.
But Gu Shen discovered that the "shadow" he had seen since childhood was the "source code of fear" at the bottom of the game.
This book is very good