"Super Mario 64" was developed over approximately three years, with one year spent on the design concept and approximately two years on production. Production began on September 7, 1994, and concluded on May 20, 1996. According to Miyamoto, most of the time there were approximately 15 to 20 people working on the game. Development began with the characters and camera system. Miyamoto and the other designers were unsure of which direction to take; months were spent selecting a camera view and layout. The original concept involved a fixed path like an isometric-type game (similar to "Super Mario RPG"), before the choice was made to settle on a free-roaming 3D design. Levels were initially sketched by course director Yoichi Yamada; he and the level designers then took notes on the key elements of level, referring back to them as they designed the level for the game. Although the majority of "Super Mario 64" features the free-roaming design, elements of the original fixed path concept remain, particularly in the three Bowser encounters. One of the programmers, Giles Goddard, explained that these linear elements survived as a means to force players into Bowser's lair rather than encourage exploration.