@ D_prOdigy,
Retro worked with Rare on Jet Force Gemini and some of the team previously, worked on 3rd person shooters. The Guy, Jeff Spangenberg, who founded Retro was also the founder of Iguana Entertainment, which produced the Turok series for the N64. Some of the staff could have followed him to Retro.
More importantly though members of Retro's Staff are Veterans. Mark Haigh-Hutchinson, who passed away this year, co-develop titles like Star Wars: Dark Forces and Rebel Assault. Nintendo fans will better remember him as the project leader and contributing programmer on such N64 games as Star Wars: Shadow of the Empire and Star Wars: Rogue Squadron. And he was integral in the development of the camera systems in the Metroid Prime Franchise, not Metroid that was all Intelligent Systems work.