Megalovania was composed by Toby Fox for Undertale, released in 2015, as the theme for Sans during the final battle of the game's genocide route. Its relentless chiptune rhythm and memorable melody helped it escape the game and spread through YouTube remixes, speedrun videos and meme edits, where it became shorthand for an overpowered opponent or an impossible challenge. Years later it remains widely recognised, which is why creators still reach for a few seconds of it to signal an unstoppable opponent has arrived.