In the case of novels or recorded music, I think a modified copyright system that might be better. One conceivable idea is that you could have the engine, which is a program, and you could have the scenario, which is treated like a novel. So the game scenario, the terrain, the characters, and so on, would be treated like a novel. And suppose that the rule for novels and things like them was that you could mail copies to your friends, but public distribution was covered by copyright. Then I presume they'd be selling copies of these scenarios, just as they'd be selling copies of novels, and the information police wouldn't arrest you if you made a copy for your friend.
Music is like a novel.
Basically, you should always be free to make copies of musical recordings for your friends. It could be okay to have a compromise copyright system covering public distribution. However, I don't think we need that. And people will do it.