Skeleton in the Mirror

[Cthulhu + no system + multiple worlds + mental illness + super fast pace] Chen Mo accidentally saw another world while working. From then on, his normal life began to break, and he was greeted by despair and silence... In the world of corpses, he gained the strange ability to transform into corpses, but he couldn't use it in reality. As the scars intertwined between the two worlds, Chen Mo began to wonder: Which one is real? When he searched for the "Mirror Lake" that returned to reality, he discovered a more terrifying truth - perhaps he was the sacrifice that connected the two worlds.