Would I be able to use music for other games?

[MrBehemoth]

It's definitely copyright infringement. In the modding world people do that sort of thing all the time, so the lines are seen as kind of blurry. It's not uncommon to see weapons and NPCs ported from one game to another, or elements of cartoons and movies used in mods. It's illegal, but people get away with it all the time.

Music is one area where the lines are more defined, however. If you use a piece of music, you are not creating another version of someone else's idea (which is fine), you are using their actual product itself. If you make an Amnesia mod, you can use Amnesia music because everyone who plays the mod has (in theory) bought a copy of the music when they bought the game. If you take a file out of Amnesia and put it in a mod for Thief, then anyone who bought Thief, not Amnesia, gets a copy of the file. Frictional would be within their rights to stop you from distributing it.

There are lots of websites where people post music that they have released on a Creative Commons licence, which means that you are free to use it in any project as long as you attribute it. There is a good list on the CC website. I would recommend freemusicarchive.org. You can filter by genre and subgenre, e.g. Intrumental > Ambient. Only problem is that it takes time to trawl through all the tracks.