Can I use popular classical music in my game as a soundtrack? I'm concerned about copyright protection. I don't plan to make money off of my game.
Will I break some law if I do that?
In most cases... also, I am not a lawyer, find one they help.
Arrangements of, and recordings of, specific performances of classical music are both copyrighted separately. This means that even if a piece in its original form is in the public domain, the piece itself is still someone's active intellectual property.
(Also, this list isn't exhaustive; get a lawyer, really.)
Then there may be a few more things to consider. But when it comes down to it unless you are an awesome musician with a lot of time on your hands to find music that is in the clear (and have a lawyer to confirm that it is) you'd save a lot of money to just license music. If you are an awesome musician, you still save a lot of time by just licensing music.
The copyright isn't on the notes of the musical work, it's on the specific recording that you will most likely run into issues with.
If you have a keyboard and play out Fur Elise and put that in your game, nobody will go after you. The musical score is in the public domain.
But, the musicians and recording company who produced a particular Beethoven recording must be paid for their production costs, as well as the fact that they sat and played the session -- as such you cannot just buy a copy of that recording and use it in your game -- you have to pay additional fees if you plan to use in something that will be further distributed.
Music goes under public domain automatically after 80 years unless specified by a certain agency - some themes and tunes cannot be copyrighted because of their widespread nature. The other thing about this particular law is that the recording of the music does not go into public domain for a lot longer. If you were to use a recording of music created in the 20's (and not continuously copyrighted) then that would be legal, but if the recording was from the 50's then you would be breaking the copyright law.
This is good knowledge to have because that means that you may record any performance that you put on if the music itself is in the public domain and there is nothing that anyone can do about it. If you can play a symphony that you have the music to then putting it in your game is just fine. Using the British Orchestra's 2007 recording of Bach is complete copyright infringement.
Be smart, play it safe, don't let something small hurt your game.
You cannot use particular recordings of songs, but you can usually use MIDI files, because they are usually in the public domain.
A MIDI file has no audio, it just has the notes of the song. But it will play like an audio file if you have a MIDI player.
Most old games from the 90s have MIDI players built-in, so you can probably add one to your game.