Some key bits:
The concept of Pikmin, for example, was borrowed directly from an unpublished RTS (real-time simulation game) proposed by a creators years before the game’s release. Thus, the official story (Miyamoto got the idea for Pikmin by observing animal life in his garden) is just a clever narrative, fabricated for marketing purposes. Mario Galaxy is another example. According to our source, three totally different versions/concepts had been proposed for what was then called “Mario 128”, but none of them made the cut. Nintendo then set its views on a promising prototype it had bought from an external source some time ago, added Mario and its friends, tweaked a thing or two, and... Here was Mario Galaxy!
Well it is known that Nintendo shelves a lot of prototypes they make and they made a ton over the years. Then again I'm not sure about the first bit it is known that Nintendo likes to put forward guys like Miyamoto as the creators of certain games that he was only involved in at a management level.
According to our source, Nintendo is in possession of a gigantic treasure trove unlike any other, so far largely unexploited. This unique policy of colossal investments into game prototypes and game design concepts has to be fully put to use.
Originally Posted by Shiggy
A Japanese developer said on some forum that they pitched some gravity project to Nintendo and they used it in SMG.