The iconic Nintendo 64 launch title and the first truly open world 3D platformer, Super Mario 64, took less than two years to actual develop. The information was shared as part of the recent leak of Nintendo information which has shed light on the history of canceled and existing games. However, in a Nintendo Power interview, the game’s creator, Shigeru Miyamoto, said that the conceptual work on Mario’s N64 launch title began in 1993 during the development of the Super Nintendo hit, Star Fox. A full year was spent on “design work” before the programmers started their work. The actual development of Super Mario 64 started on 7th September 1994 and was completed on 20th May 1996.
The Nintendo 64 launch title’s “Period of Creation,” the document reads, started on September 7, 1994 and lasted until May 20, 1996, which was one month before the game’s June 23 release in Japan. All told? 622 days.
The text file also suggests that work on an additional revision took place over another 15 days, spanning from July 15, 1996 to July 29; one might assume this was preparing Super Mario 64 for its September 29 release in North America.Kotaku.com