Shigeru Miyamoto has revealed that he originally intended for Super Mario Galaxy 2 to be developed within a year - which would have seen it release in time for Christmas 2008 if all had gone to plan.
During the latest 'Iwata Asks' interview (via Andrisang), Miyamoto admitted that the game was originally referred to internally as 'Super Mario Galaxy 1.5', apparently "to keep the staff from trying too hard". With the game system and level structure already done for SMG1, all Nintendo wanted to do was make some new levels and throw it out there within a year - and SMG1 was out Christmas 2007.
But, Miyamoto goes on to explain that as the designers tackled new levels they began to realise ways in which they didn't fully push the original game's sphere-based design, and thought of more interesting ideas to implement. And so the game has instead taken two-and-a-half years.
Had Nintendo revealed its launch plan originally, it'd technically have been delayed by a year-and-a-half. And the internet would be going mental. But it didn't and all is rosey. Are you learning anything here, Polyphony Digital (GT5 developer)?