UNDERTALE Soundtrack is a soundtrack album by American video game developer and composer Toby Fox, released in 2015 for the indie game Undertale. The game's soundtrack was entirely composed by Fox with FL Studio. A self-taught musician, he composed most of the tracks with little iteration; the game's main theme, "Undertale", was the only song to undergo multiple iterations in development. The soundtrack was inspired by music from Super Nintendo Entertainment System role-playing games—such as EarthBound and Live A Live—bullet hell series Touhou Project, the chiptune band Anamanaguchi, as well as the webcomic Homestuck, for which Fox provided some of the music. Fox also stated that he tries to be inspired by all music he listens to, particularly those in video games. According to Fox, over 90% of the songs were composed specifically for the game. "Megalovania", the song used during the boss battle against Sans, had previously been used within Homestuck and in one of Fox's EarthBound ROM hacks. For each section of the game, Fox composed the music prior to programming, as it helped "decide how the scene should go". He initially tried using a music tracker to compose the soundtrack, but found it difficult to use. He ultimately decided to play segments of the music separately, and connect them on a track. To celebrate the first anniversary of the game, Fox released five unused musical works on his blog in 2016. Four of the game's songs were released as official downloadable c