C3. First, what could C mean? Covenant? Cortana? Cryptum? Code? Chief? Chaffing?
What about 3? 3 in 1? Like a trinity of some sort? Maybe Chief, Cortana, and the Didact become 1 somehow. Or maybe, 3 new games? 3 Sets of Weapons, 3 maps, Maybe it is code for See three? Maybe it is telling us to look at the Halo 3 logo of play Halo 3? How about the amount of times GermanShepherdD couldn't get outside to pee?
Who knows. So many mysteries to solve!