I have beaten this before and the final fight with the boss was challenging but amazing. I am re-downloading it and am going to see if I can make a special XBLA HUD for it.
A 17-level single player scenario. The predecessor to Marathon: Phoenix. Many assets for Phoenix came from this, as well as some of the storyline beats, like that of the Renegades and a poorly written evil AI.
This scenario was released back in September 2006. It's hard, and it's not very good; fixes and updates went into Phoenix instead. This is presented just as a historical document, I guess.