FREE MUSIC IN STEAM (Can add without base game!)

You can add these soundtracks (DLC) in your library, even if you not have a base game or she sold for the money in store.

Some DLC sold in the store for real money, for example soundtrack for Frostpunk, but you can add him in library - free!

Little Inferno Soundtrack - https://steamdb.info/app/1270140/ (Base game not free)
7 Billion Humans Soundtrack - https://steamdb.info/app/1270120/ (Base game not free)
Human Resource Machine Soundtrack - https://steamdb.info/app/1273200/ (Base game not free)
Master of Orion: Soundtrack & Score - https://steamdb.info/app/468020/ (Base game not free) [DLC hide in the store]
Scythe: Digital Edition - Soundtrack - https://steamdb.info/app/893130/ (Base game not free)
Cymatically Muffed - Soundtrack - https://steamdb.info/app/1105750/ (Base game not free)
Sector Six OST - https://steamdb.info/app/469520/ (Base game not free)
Odyssey Soundtrack - https://steamdb.info/app/992770/ (Base game not free)
The Search Soundtrack - https://steamdb.info/app/720110/ (Base game not free) [Can receive game free april 13-14]
Nyanco Dream Soundtrack - https://steamdb.info/app/1257730/ (Base game not free)
OSK - Soundtrack - https://steamdb.info/app/1210950/ (Base game not free)
Frostpunk Original Soundtrack - https://steamdb.info/app/966350/ (Base game not free, DLC too not free in Steam store)
Nyanco Channel Soundtrack - https://steamdb.info/app/1251180/ (Base game not free)
Colum and His Friends: Soundtrack - https://steamdb.info/app/1225450/ (Base game still not released)
Frontier Pilot Simulator Soundtrack - https://steamdb.info/app/1253560/ (Base game not free)
The Executioner Soundtrack - https://steamdb.info/app/1249650/ (Base game not free)
Dying Light Original Soundtrack - https://steamdb.info/app/798540/ (Base game not free)
Walden, a game - Soundtrack - https://steamdb.info/app/1044710/ (Base game not free)
The Void Rains Upon Her Heart - Soundtrack - https://steamdb.info/app/810530/ (Base game not free, DLC too not free in Steam store)
Super Arcade Racing Soundtrack - https://steamdb.info/app/1192110/ (Base game not free)
Sable's Grimoire Soundtrack - https://steamdb.info/app/941900/ (Base game not free)
Candice: Da Instrumentalz - https://steamdb.info/app/887430/ (Base game not free)
Tomboys Need Love Too! Soundtrack - https://steamdb.info/app/942100/ (Base game not free)
Tallowmere – Soundtrack - https://steamdb.info/app/1225360/ (Base game not free)
Areia: Pathway to Dawn - Soundtrack - https://steamdb.info/app/1227670/ (Base game not free)
An Octave Higher - Basic Soundtrack - https://steamdb.info/app/415430/ (Base game not free)
Unhack - Original Soundtrack - https://steamdb.info/app/343720/ (Base game not free)
Squids Odyssey Soundtrack - https://steamdb.info/app/927660/ (Base game not free)
Monster RPG 3 Soundtrack - https://steamdb.info/app/885040/info/ (Base game not free)
TAL: Arctic 3 - Soundtrack - https://steamdb.info/app/932840/ (Base game not free)

Other:
Galactic Rangers VR - Digital Artbook - https://steamdb.info/app/1246300/ (Base game not free)