The soundtrack of Blade Runner by Vangelis is nothing short of a milestone in both the Cyberpunk science fiction subgenre and Electronic Music in general. Especially "Main Title", "Love Theme", "Blade Runner Blues", "Tears in Rain" and "End Titles".
The contrast between the various "official" versions and the famous "workprint" version of the scene where Rachael watches Deckard try to clean himself up after almost getting beaten to death is a great illustration of how music works in movies:
In the workprint, creepy dissonant noise music highlights that Deckard is vulnerable and Rachael could easily kill him at that point if she decided it was her best chance at survival and freedom.
In the later "normal" cuts, romantic music implies Rachael feels sorry for Deckard and protective of him. The entire meaning of the scene is completely different, even though nothing changed except the music.
Then there's the torch song "One More Kiss, Dear", whose lyrics encapsulate the plot.
A beautiful and tear-jerking reprise of "Tears in Rain" when K brings Deckard to his daughter and looks like he's about to die from his wounds. It is the only moment where Zimmer and Wallfisch used a Vangelis track.
In the original score we have the ominous 2049, the sweeping Mesa, and the thunderously climactic Sea Wall.
The film was to be scored by Jóhann Jóhannsson, but he left production for undisclosed reasons and his contributions were removed from the picture. As the teaserand trailer showed, he remixed themes of Vangelis to invoke both thematic continuity and nostalgia of the original.
, the sweeping Mesa