Maybe I’ve been watching too much Game of Thrones (and Star Wars is on my mind as well), but I’ve been thinking about how H6 can utilize some shocking deaths in order make for both an interesting story in itself, and give more meaning to some parts of the H5 story.
Essentially the ending sequence of H6 could be – Cortana kills Locke.
It would be a suspenseful, scary level akin to when you first meet the Flood in H1 – this feeling of being ‘hunted’ (<- bc of the whole ‘Locke is a hunter’ thing – you get it).
The story would go something like,
Cortana has taken over the Infinity and taken everyone on board prisoner. Contained on the Infinity is the AI master plan for assuming the Mantle (or any other generic super secret plan located deep in the enemy base).
In the levels leading up to the final sequence, Osiris and Blue Team have been deployed in various areas to find a way aboard the Infinity. Their objective is to save Lasky (maybe draw a parallel to Flood-infected Keyes by having Lasky infected by the Logic Plague?) and the others, as well as steal the AI master plan and send it back to base.
gameplay note – they could easily replicate the H4 Mantis level (in this case it would be ONI/Hannibal variant), but they could also make Infinity an open environment that the player has to actively search through and figure out where to find everything, as opposed to walking a linear path to the objectives.
At some point Osiris/Blue Team rescues everyone and gets the plans, and gets ready to escape the ship and head back to base. But, unfortunately for whatever reason, one of them has to stay behind in order to let the others escape (maybe one person has to remain behind to hit the escape button, who knows).
Basically Locke sacrifices himself to save the rest of Osiris/Blue Team. This would conclude the final level – now, on to the hidden mission/epilogue sequence.
Now, Locke is alone on Infinity with Cortana and the Warden out for blood. They are searching furiously through the ship in order to find him.
Locke, with no assistance/AI/anything to help him, knows he will have to save himself. He locates an escape pod somewhere in Infinity, and stealthily makes his way to the pod. He fights his way through (whoever the enemy is - Forerunners, special Cortana-created enemies, whatever) enemies in order to reach the escape pod.
But, just as he gets close, Cortana’s haunting voice pierces the silence – “Found you.” (cue Inception-style horns)
Final battle sequence between Locke and Cortana/Warden enemies – Locke pushes through, but is mortally wounded.
He now comes face-to-face with Cortana. Cortana tells Locke that she will not kill him, but instead use him to bargain with the UNSC (idk what she would want from the UNSC, but imagine there’s something she wants to trade Locke for).
Cortana then taunts Locke over his current state of isolation – he is alone on Infinity with no one else and no one to save him. Cortana relates his isolation to her own isolation – remember that she originally planned to take the Chief with her, but was denied this when Locke/Exuberant Witness saved the Chief.
In response, Locke, struggling to stay alive but fighting harder than ever before, says with defiance: “You were built, not born.”
Cortana is enraged. In Cortana’s new world/universe, denying the nature of an AI’s existence is basically the worst thing you can say to an AI - the highest insult.
Cortana, with finality, emphasizing each word: “Changed. My. Mind.” (making clear that she believes in her own consciousness, autonomy, and agency)
Cortana takes on a new, heretofore unseen, physical form in front of Locke, and stabs him through the chest with a Knight blade or something of the sort.
Cortana kills Locke. Back on the UNSC ship, Osiris/Blue Team watch the screen with Locke’s vitals on it, desperately trying to figure out how to save him. All of a sudden, his vitals zero out.
Osiris and Blue Team are first stunned, then horrified, then break down. The closing shot is of Osiris despondent at the loss of their leader, while the Chief looks at them in regret and sorrow.
What is the point of this ending? Well H6 could go in any direction, but it could also give some greater significance to H5’s story with this ending. The key H5 plot and dialogue references included above would help players feel like playing H5 wasn’t a waste of time and didn’t irreversibly damage the overarching Halo story.