Megalovania was composed by Toby Fox for Undertale, released in 2015, where it plays during the boss fight against Sans on the genocide route. The track had earlier versions in other projects, but the Undertale arrangement made it widely known online. Its driving rhythm and simple looping melody made it easy to remix, speed up and reuse in fan videos, which led to countless variations including instant and sped up edits. It remains closely linked to difficult boss encounters and determined characters in gaming culture.