This site makes for interesting reading:
http://tvtropes.org/pmwiki/pmwiki.php/VideoGame/Marathon?from=Main.Marathon
Opening quote:
Marathon is a series of groundbreaking Science Fiction First Person Shooters developed for the Macintosh by Bungie Software. The game has a ridiculously in-depth story even compared to modern games, and its plot can get very complex and sometimes even headache-inducing. In the pseudo-random clues provided by in-game terminals, it comes close to William Gibson ambiguity: lots of surreal textual scenes (in the middle of convincing runtime errors) will scratch your cortex; plausible quotes from technology design documents, history records, and standards guidelines that make you wish no AIs will ever be put in working order.
Heh....
Cheers
Hamish