i have head they do but i dont know if i believe it, though my friend assures me its true. apparently if you do it on legendary at end of credits it tells you halo 3 will be out in febuary 2005, as apparently halo was so big when they had completed it they decided to cut the game into two. things that support this is in all the orignally demos of the game the conflict was set on earth in heavy conflicts with the covernet completely invading SPOILER like at the end of the game not just the skirmish you get at the begining. none of these were in the actually game. however against this is you d expect it to be everywhere on the net + it woudnt be a full sequel just an expansion pack really but meh