Not much of an idea, because I haven't played it yet--I've been stuck in college. Someone spoiled the ending and I was all ¯\_(ツ)_/¯ so I gave up trying to go dark, but I haven't seen a play by play of the game itself. I'm waiting for Saturday to do that when a friend and I can go through it together, and when I am home with my Xbone. But based on what I have read, I DO find it really weird that Cortana is the main villain--you said elsewhere that the lack of build up to that is jarring and I agree. On its own though I like it, because for one it echoes Halo CE's original plot where Cortana goes evil halfway through iirc, and secondly, it makes sense that all of these ancient and Rampant Forerunner AI's would preserve their megalomaniac ideas and try to retake the Mantle themselves--it ties in with their plans for the Composer mentioned in Halo 4, that the Composer would have made the Forerunners immortal, presumably allowing them to continue their work. Most importantly though Cortana is acting as our own Medicant Bias, just less omnicidal and more Big Brother. I feel as though she is our Precursor test, or at least related too it--she was "cured" of rampancy by the Domain, so there's no telling what it did to her precisely. It is a Precursor intelligence after all. I'm iffy overall. The lack of proper buildup is jarring. For as good as it was the Hunt the Truth campaign has been a wash, at least in so far as tying in with Halo 5, and I get the sense that Halo 5 is less a story on its own and more of a prologue to Halo 6. Which I somewhat expected, the second act in a 3 act structure is typically A) the darker one and B) the one without a beginning or end. I am fine with it blowing open so many doors and leaving with so many questions because I know there is a third game coming--people were left flabbergasted after Empire Strikes Back ends with Han being captured and Vader revealing the truth about Luke's heritage, but it is still widely considered the best one, so the hanging threads aren't the issue. It's more the lack of narrative meat on the story; it fails to live up to the hype that Hunt the Truth gave it. Again this is all based on what I have read. I'll have a more accurate opinion when I play it myself; I am sure I'll love it, but whether it'll top Halo 4 remains to be seen for me.