Turok: Dinosaur Hunter
Entire source: download
•From what I've heard, no one has been able to build it. Anecdotally, it's an earlier version than the final release.
"In an interview with GamesRadar, lead designer David Dienstbier confirms that the first South Park Game for N64 was based on the Turok Game Engine, so much of the code released will have been compiled for South Park too."