Rainbird on 15 May 2011
So if we want to exclude emulators, it could go something like this:
"Every videogame is exclusive to a subset of all platforms, where the game has been officially released on each platform in the subset. If a subset of platforms exist such that the game has been released for each of those platforms, but also on a platform outside of that subset, then that the game is not exclusive to that subset."
