What is your favorite song that has never been released?

For me, Alan Walker - Lights & Shapes. a song that was created after Force. the reason why the song was not released is that Alan Walker signed with Sony to do the vocal remake of Faded, and which would later become a worldwide hit. the same story happens to Locutus, supposed to be the 4th release of NCS, with a teaser that had been published on SoundCloud except that it was deleted by him, there is indeed an archive but it is a lost media because of the missing audio.