Gaster Blasters first appeared in Toby Fox's Undertale, released in 2015, as the signature attack of Sans during the Genocide route boss fight. The floating skull cannons are named for the mysterious W. D. Gaster, a character referenced only in hidden lore. The charging whine became widely reused outside the game as fans made battle recreations, animations and memes, isolating the charge from the blast itself. Its brevity and rising pitch made it a standard shorthand online for an anime-style energy weapon powering up before firing.