A recording of La Campanella. This piece is extremely difficult, with the key being just one, but a very important, part of that

"Suffocation of the Heart, Lamentations, Life-Long Struggles. A negative look at the experiences of life, competition, growth."

More commonly written as G♯ minor for ease of reading, this key is almost never used. The one claim to fame of this mysterious key is its use in the piece "La Campanella." You'd know the piece if you heard it.