Lost Silver is a creepypasta surrounding a used Pokémon Silver Game Boy cartridge, first known to have been posted to a 4chan thread around June 6, 2010. In the corrupted save file, Unown characters spell out death messages like "LEAVE" and "DYING," Pokémon literally die rather than faint, and the tale ends with a battle against a ghostly trainer in permanent darkness.
The heart of the horror is the corruption of a familiar game. The process by which a bright game everyone knew becomes something else, filled with the signs of death, turns memory itself into something to distrust. Lost Silver is regarded as the foundational work that established the framework of the "haunted game" subgenre.