It's one of their last chances at Halo proving COD was a fluke. That they didn't waste years of memorizing the maps and that getting 50s wasn't a complete waste of time in respects to the present year. They can say they had fun all they want, but Halo can only grasp onto nostalgia and slowly dying dedicated servers on PC instead enjoying the solid backing and appeal COD enjoys from Activision's marketing and yearly distribution of one more new COD game while Halo4 to 5 drags on. They had to watch their franchise bend to COD while COD really never changed, and even now with it embracing Sci-Fi elements It cements a nagging doubt that COD will even out sci-fi Halo.