[FREE][STEAM] 422 Soundtracks you can activate in Steam (legal, without paid base game, etc.)

This is a list I've made myself of all current soundtracks, audiobooks, drama CDs and sound stuff that you can add for free and legally to your Steam library. You shouldn't even need the base game to add them (read below for a caveat).

I started with this thread about the same subject: https://www.steamgifts.com/discussion/XCks6/free-music-in-steam-can-add-without-base-game
So thanks to everyone there for their contribution. That thread hasn't been updated in more than one year, so I think it's better to make a new post than to use necromancy.

I used it as a start, getting more than half of this list from there; then removed the things no longer available, used some searches in SteamDB and Steam Store to find more, and since now these products have the nice blue button "add to library" in the store page, I skipped the SteamDB step (but it's in the instructions nonetheless).

The list is not prone to errors. For example, I might have been able to activate one soundtrack because I already had the base game, and it's really a bother to check for those. It's also a bother to check which ones that I already had could be activated by others without the paid base game or with a free game, so yes, there might be stuff not there, or stuff there that shouldn't be. All things you need to know are in the text as caveats, instructions and comments, and then the list of the links of all these free products you can add.

Everything is in this PasteLink link. Feel free to share the link anywhere you want. Last update: 03-Feb-2025 - Feb 2025 update.
https://pastelink.net/d12v8s82

You can also report stuff (in the way explained in the list) in this thread, I'll try to update the list, but I might not be available or active. Thank you.

New free OSTs (please don't add normal DLCs) are always welcome. Finding something that can't be activated anymore is also nice to report to help the list be as healthy as possible.

SPECIAL NOTE: from Feb 2025, I'll only issue one update monthly; I reserve to my discretion to not do an update if I think it's too small.

Please don't report when a store page says "X is no longer available on the Steam store", or it redirects to the store home page; they can still be activated, just not through the store.