The song "Megalovania" by Toby Fox made its third appearence in the 2015 RPG "Undertale".

The statement is true because "Megalovania" did indeed make its third appearance in the 2015 RPG game Undertale. The song was initially composed by Toby Fox for his webcomic called Homestuck in 2009, and later used in the video game EarthBound Halloween Hack in 2008. However, it gained significant popularity when it became a boss theme in the indie game Undertale released in 2015. Therefore, the song made its third appearance in Undertale, solidifying its recognition and association with the game.