Let's say that I, citizen of Alicetopia in the EU, were creating a derivative work of a copyrighted composition. This would be a heavily modified instrumental rearrangement of an existing song, to the point where it would be basically unrecognizable unless you already knew what you were looking for. Hypothetically, said song would have been written in the late '80s by a Bobvillian band (outside of the EU). (Would it matter which country the song was recorded in? Because it would be yet another country, heh).
Now, to further complicate the issue, assume that I were planning to license usage rights to a group of friends for them to use as background music in an indie videogame of their making, that said friends lived in Charlieland in the EU, and that they were looking into digital distribution of said videogame, which could potentially entail selling the game in other countries, in and outside of the EU.
So my question is, what countries' copyright laws would my friends and I need to abide by in order to decide whether we could use such a track and whether we would need to pay royalties? Alicetopia? Bobville? Charlieland? Potentially every single country where we decided to distribute the game?