The thing about that though is an engine is not the game, and it's common to separate game content/assets from it's engine. It's not so clear that other softwar

The thing about that though is an engine is not the game, and it's common to separate game content/assets from it's engine. It's not so clear that other software breaks down in the same way; should the whole thing be free, or should only the "core"? Maybe applications can open their libraries, but not the apps themselves?