"Megalovania" is the Greek word for "Megalomania", which means "obsession with the exercise of power, especially in the domination of others". It is also the name of the song played when you fight Sans in Undertale. The song might be called this to relate to the abuse of your power to reset and alter the timelines.
The Megalovania Effect:
Any song that is modified by any means but majority to most of the modified songs still sounds really good. At this point, We can conclude Megalovania is the first to achieve that in humanhistory.
*the one who came up with this is: TwoSling_Mappings on YouTube
Megalovania is the song that plays when you fight Sans. The final boss of the Genocide Route of Undertale. The word means the feeling of sins crawling on your back.