: How can 4 have a 3 year development cycle if its built off of reach, a game
: that didn't release until 2010? unless Bungie gave them a build of Reach
: in 2009 which I doubt them doing.

There's a lot of game development that happens before you write the first line of code, especially for a new studio. There's hiring staff, setting up the office, designing the story, creating concept art, etc. 343i was created while Reach was still being made, and they've been working on Halo 4 all that time.