Actually, I don't know about that. When I download, it shows an estimated file size. Originally, the file I received would be that size, but after a second download for a specific platform, the estimated file size is quite a chunk smaller than the estimated file size. Except possibly for the N64. I can't remember how that worked. The gist of what I'm saying is that I think they don't duplicate much of the emulator, but perhaps the settings they want the game to work with on an existing emulator you've already downloaded.