The virtual hills are alive with the sound of music, thanks to Steam wresting soundtracks from the videogames they were yoked to. As of today, developers can sell soundtracks independently rather than as DLC, which means you won't need to buy or download the games themselves. Videogames are defunct now. Let us all escape into the superior medium of sound.
The change isn't retroactive, but Valve have made it easy for devs to convert previous DLCs into soundtracks you can just straight up buy. New games can still sell their soundtracks as DLC if they're feeling mean.
The new system also supports higher quality file types than MP3s, which will be larger and optional. Valve are introducing a new interface for playing soundtracks through the Steam Library too, and anything would be an improvement over Steam's current terrible built-in music player. For people who prefer to use their own player, Steam will now let us pick one single music directory for soundtracks to go into, rather than scattering them across different game subdirectories. I am a bit baffled this has been bad for so long.
Developers can also sell soundtracks for games that aren't on Steam, which I'm hoping will encourage ancient earworms out of the woodworks. Terry Cavanagh's self-composed soundtrack for flash game Don't Look Back springs to mind, though I now notice he's got that up for free on Bandcamp anyways.
Still, more people listening to more good music is a good thing, and in that spirit I quizzed the RPS treehouse for soundtrack recommendations. Katharine pointed at Mutazione, Ori And The Blind Forest, Undertale, and Hollow Knight. She also pointed at the soundtracks for Octopath Traveller and "every Final Fantasy game", which Steam doesn't actually sell. Perhaps that will change.
Alice Bee recommends Sayonara Wild Hearts, while Sin dubs Hotline Miami "probably too obvious" but "pretty much the only game soundtrack I've ever put on with other people in the house". I'll one up the obviousness and just gesture at every game made by Supergiant. Darren Korb is a wizard, and the way Bastion marries its music to its story is spellbinding. Maybe don't listen to it in isolation first.
Valve go into more detail about the update here, where they also mention they'll release the new features "in a wider way, including a sale event, on January 20th".