I'll probably be uploading the soundtrack soon enough, though
I wanted to give credit for all the songs right here anyway.

Sylux Appears/Intro: Sylux Jingle - Metroid Prime Hunters
Title Screen: Select Menu - Metroid Prime Hunters
File Select: Sylux's Theme - Metroid Prime Hunters
Landing Site: Landing Aboard the BSL - Metroid Fusion
Item Room: Boss Defeated / Alimbic Cannon - Metroid Prime Hunters
Item Jingle: Get Weapon - Metroid Prime Hunters
Electricity Area: Electroman Adventures - Waterflame
Boss Tension/Defeated: Tension Before A Confrontation - Metroid Fusion
Red Eye (Electricity Area boss): Ruby Delusions - Sonic Mania
Ice Area: Dr Wily Stage 1 and 2 - Mega Man: The Wily Wars (Mega Man 2) 
F.R.I.D.G.E. (Ice Area boss): Final Bosses Theme - Mage Kanade's Futanari Quest (NSFW)
Fire Area: Lava Spring - Earthbound
Arachnus's Revenge (Fire Area boss): Meta Knight's Revenge - Super Smash Bros Brawl
Darkness Area: Team Rocket Hideout - Pocket Monsters Red and Green and Blue and Yellow
Yakuza NEO: Spider Dance - UNDERTALE
Water Area: Dire Dire Docks (in-game version, Jolly Roger Bay version) - Super Mario 64
SERRIS (Water Area boss): S.E.R.R.I.S. (Dread-style remix) - seregoss https://www.youtube.com/watch?v=FyDYjR0MwdY
Gravity Area: The Final Fight (Genesis) - Sonic 3D Blast
Final Corridor: Metroid Queen Area - Metroid II: Return of Samus
The Nightmare: Metroid Fusion Nightmare Theme Extended Arrangement - Kassil https://www.youtube.com/watch?v=cw4aVaKTMIA
Black Hole Collision Imminent: Escape - Metroid Prime 2: Echoes
Mission Accomplished/Credits: Credits - Metroid Prime Hunters
Secret Room: FitMC makes SHOCKING APPEARANCE in METROID ZERO MISSION ROM HACK?! | S4E1 [YTP] - Roebloz and HardwareFahrrad https://youtu.be/Ce5VFz2jajQ
