Megalovania was composed by Toby Fox and first appeared in earlier projects before becoming famous as the Sans boss theme in Undertale, released in 2015. Its relentless riff spread far beyond the game through remixes, covers and meme edits on video and soundboard platforms. Players came to associate the first notes alone with a notoriously hard fight, so creators now use even a three second burst as shorthand for danger, determination or a joke battle that is about to escalate.