Super Mario has a decent amount of earworm-like tracks (just listen to the Overworld theme and the Water Theme and, I guarantee, you won’t be able to stop humming those melodies).
The Ghost House theme, with all its variations, is perhaps more of an unsung hero, but youtube user String Player Gamer Diwa de Leon turned that eerie melody into a polyphonic wonder.
And for that purpose, he did not even need to modify Koji Kondo’s original score: he just substituted every “instrumental” note with his voice!
If you are on a spooky music kick, we encourage you to peruse String Player Gamer’s channel: their version of Zelda’s Song of Healing, and their Castlevania Rock Medley make for a perfect Halloween night soundtrack.