Awesome Music / Storyshift

Official Soundtrack (Reboot)

• "Unwarranted Confidence" plays for the Alphys fight. Obviously based on "Unfounded Revenge," it reflects the false bravado she goes in with.
• "The Pride of Prince Papyrus" goes for a different feel than most Heartache analogues, using bombastic yet wavering trumpets to reflect Papyrus's royal status and outer confidence.

Preboot / Fan-Made Songs

Whilst the creator has stated an official soundtrack would use original themes, some of the music created by the fandom with the AU in mind is very nicely done.

• For instance, "Heartrousle", an idea of a battle theme for Toriel!Papyrus, as well as its Mario Paint remix.
• "Histrousle" by Keno9988iv, a theme for the boss battle against Papyrus!Asriel. It combines Bonetrousle and His Theme to create a catchy and upbeat theme, fitting for the character it goes along with.
• Also for Asriel comes "Defender of All Monsters!" and "Hypertrousle" from Lucaspucas, remixing Finale into themes in the style of "Nyeh Heh Heh!" and "Bonetrousle" respectively, creating upbeat and heroic themes that fit their character very well.
• "Attack on Umbra" by Lucaspucas. An intense, rocking cover of Undyne themes in the style of "You Will Know Our Names", of all things.
• Dorked provides the fantastic "see ya. + sans." for Asgore!Sans, remixing the skeleton's original theme with parts of Papyrus' (and even a little bit of "Heartache" towards the end due to the original "ASGORE" incorporating the Royal Guard captain of its own universe's theme) for an incredibly intense and emotional battle theme.
• From ShayminPichu of Soundcloud, there's "Your Ghost Nightmare" and "Final Tune", which are potential battle themes against Photoshop/Omega Asriel!Napstablook. It's much calmer sounding than the originals, but it still faintly has the same feelings of despair, slowly being replaced with hope.
• "Battle Against a True Parent" by Whirligig231 is a beautiful battle theme for Undyne!Toriel on the Genocide Route. It features the same heroic and badass tone of the original, but also adds parts of 'Heartache', 'The Ruins' and 'Fallen Down' to cement the somber emotion Toriel could feel as if she hoped better of you, but then it kicks up at the end to show that even if she may not wish to hurt you, she understands the threat you pose and it is her duty to stop you.
• Keno9988iv's "MEGALOGLAMOUR" for Chara!Mettaton, a remix of "Megalovania" with Mettaton lietmotifs, based on the theory that "Megalovania" is Chara's theme.
• On the other side, there's "The Monster In The Mirror" by Jamangar, which is instead for Sans!Chara during the same battle, going by the theory that "Megalovania" is Sans' theme and incorporating "Megalo Strike Back" and "Once Upon a Time".