Let me contemplate Halo for a minute...
Starship Troopers by Robert A. Heinlein featured green power suite wearing elite soldiers. I see this classic forfather as inspiration for Soldiers of space:
http://img263.imageshack.us/img263/2769/sop.png
And we get another version of the armor with the Starship Troopers GCI adaptation:
http://img27.imageshack.us/img27/3689/sopu.png
This one book is also a heavy influence on both the Warhammer 40k series, Starcraft series, and Aliens and the predator series. I could go into detail about that but lets stick to the point:
WHY is halo considered such a good game when its only really new innovation into sci-fi AT ALL was the giant rings, witch only get prominently featured in the first game?
The gameplay was solid and fun. But really from the first game the plot was weak, and smelled of capitalistic pursuit of tried and true themes.
Consider what they really had after the first game.
-Suspiciously familiar power armor worn by a character that might have been a robot for all we can tell
-Aliens (really!?)
-head jumping aliens that turn you into a zombie:
http://img268.imageshack.us/img268/4927/soplz.png
(oh by the way Gordon Freeman is still waiting for his royalties, thats a half life headcrab)
-And last but not least, you are the only survivor of the game.
(and from this point on the event of the first game an inconsequential)
The rest of the series tried to evolve the game into some original thinking, but everyone seems to think those games got worse and worse. Sooo... in conclusion, maybe we should stop milking a dead cow.