Dark Fountains are a central element of Deltarune, Toby Fox's episodic role-playing game first released in 2018 as a follow-up in spirit to Undertale. In the story, fountains of darkness create Dark Worlds inside ordinary places like classrooms and closets, and sealing them drives much of the adventure. The fountain sound became familiar to players from those story moments and cutscenes. Online, fans lifted the quiet ambience for edits, memes and fan projects, using it as shorthand for a mysterious portal opening or a world shifting into fantasy.