Seems to be 3 audio assets used for for the music in 5-1. 'abyssalcavedrone', 'abyssalloopfastcalm', and 'abyssalloopfast'. All I have done is upload it to SC.

0:00 abyssalcavedrone (Drone Intro)
0:42 abyssalloopfastcalm (Calm Loop)
2:50 abyssalloopfast (Combat Loop)

enjoy the sax

devilmayquake.com

ULTRAKILL - Deep Blue (has Sax)

22 - Meganeko - The Cyber Grind

KEYGEN CHURCH - Tenebre Rosso Sangue (Calm)

ULTRAKILL: PANDEMONIUM/WAR

ULTRAKILL OST: PANDEMONIUM P-2 Theme #2

I DO NOT OWN THIS

original by Keygen Church - https://youtu.be/KTCC053fLqs

Ultrakill is by Hakita

KEYGEN CHURCH - UltraChurch

Heaven Pierce Her - The World Looks White (ULTRAKILL 7-1 Theme #1)

Heaven Pierce Her - Hear! The Siren Song Call of Death (ULTRAKILL 7-2 Theme #2)

Heaven Pierce Her - War Without Reason (ULTRAKILL 7-4 Theme)

Credits to Hakita and Heaven Pierce Her for this banger!

Heaven Pierce Her - Dead Heat Pulse (A Heart of Cold) (ULTRAKILL 0-E Theme #2)

In Absentia ΛΟΓΟΣ (ULTRAKILL 8-1 Theme)

Ambient Dreamscapes for you to enjoy. Relax, unwind, meditate and chillout

ULTRAKILL - Deep Blue (has Sax)

Neo