From Another Point of View
Back in the day, when a company (or an individual) wanted to make a game, they’d usually choose a platform and make it. When a game console company (Nintendo, Sega, etc.) made a game (or payed for one to be made), it was for their systems. You didn’t see “Super Mario Brothers” on any system that didn’t have “Nintendo” written on it.
Nowadays, that isn’t the case. Many games are made by third parties, and though politics and various deals can still result in a game being released for only a single platform, most games are released for at least two. Actually, since the PC is now as good a “console” as others (well, maybe not as good), even games released by Microsoft for their XBox, are released on another “platform” as well 
. Anyway, I digress.
