Megalovania
The song that plays when you fight Sans in undertale, genocide route.

Undertale is a game about a human that has fallen into the underground. Long ago, the humans and monsters went into war. Humans won, locking monsters into the underground. It is said that seven monster souls are equal to ONE human soul, so it's obvious why they lost.
G1:"Dude! I just beat Sans!"
G2: "Nice, how long did it take?"
G1: "Hours... I'm SICK of Megalovania, though."