Check out what they had to say on their website or have a look at the below excerpt.
How is this game so damn popular?
Contributions to the N64: Major. Beyond uttering the first uncensored full-fledged dirty words (there was even nudity in the European version) on the N64, Shadow Man brought a rare mature and entertaining game to the console. A game that's actually carried by a believable African-American lead character is something we didn't know we were missing until we had it. Shadow Man is one of the strongest, most uncompromising characters in any game on any platform. He could've easily been watered down as he made the jump from comic book to videogame, but we're extremely glad he wasn't it. Let's hope he continues to be the definitive badass in the upcoming movie.