This is going to be a bit of a credit sequence, listing off all of the songs used in case anyone wants to give these tunes a listen.


L4D1:

Blood Harvest: Scattle's remix of Quixotic https://www.youtube.com/watch?v=oY9xGeWHYEE
Dead Air: ALEX - Demons
Death Toll: ALEX - Mainframe
No Mercy: Tonebox - System Error
Crash Course: Tonebox - Cyber Realm

L4D2:

Vanilla Campaigns: Track 5 - Hotline Miami's Unreleased Soundtrack
The Passing(Finale Saferoom Music): FANTASIZER - Breaking Point


Hunter's Theme: Carpenter Brut - Warzone
Boomer's Theme: Mega Drive - Acid Spit
Smoker's Theme: Mega Drive - NARC
Charger's Theme: Future Club Mashup by GoldenToparican on youtube. https://www.youtube.com/watch?v=x5kPLb-b4qQ
Spitter's Theme: Gesaffelstein - Pursuit
Jockey's Theme: Carpenter Brut - You're Mine
Witch's Theme: Scattle - Bloodline
Witch Bride's Theme: Mega Drive - Slum Lord
Tank's Theme: Perturbator - Complete Domination


For L4D2
ALEX - Nyctophile

For L4D1
Tonebox - Nocturn


iamthekidyouknowwhatimean - Run


L4D2: Scattle - Remorse(note: i played around with some of the free tools Audacity provides, feel free to ask me to revert any sort of "editing" on the tracks.)

L4D1: Perturbator - Venger

L4D2 Loss: Track 5 - Hotline Miami Unreleased Soundtrack

L4D1 Loss: ALEX - Mainframe

L4D2 Player Death: iamthekidyouknowwhatimean - We Love You Celestial

L4D1 Player Death: Perturbator - Sentience

Dead Center: Gunship - Technoir(Carpenter Brut Remix)
Dark Carnival: M.O.O.N.'s remix of Le Perv https://www.youtube.com/watch?v=REPD9BEKqTE
Swamp Fever: Perturbator - Humans Are Such Easy Prey
Hard Rain: Tokyo Rose - End Game
The Parish: Cinimod - The Rumble


Save Me Some Sugar Replacement: Mega Drive - Slum Lord


All tracks used are just edited versions of their respective themes, i.e., the jockey's vassalationhit file is just its track reversed. (NARC and Warzone were reversed with reverb added)