The multiplayer map Guardian from Halo 3 was originally part of an actual level in the camagin that was cut during development. The level took place in the Guardian Forest, and was to feature Guardian Sentinels as fightable foes throughout. The forest itself was to be littered with Forerunner stuctures that would be explorable as you progressed. The multiplayer map was one of these structures. What the campaign mission would have focused on, or what objectives were to be completed, are unknown, as again, this was cut at some point. Another piece of this level was also removed and spliced into The Covenant level.
Guardian Sentinel:
Hmm. Where have we seen Guardian Sentinels before? Ah yes. Halo Origins! The Guardian Sentinels can be seen escorting/protecting the Key Ship.
And this is not the only hidden gem we can find from this map. Also, in Halo Origins, we are given a very brief scene, which I've covered before but I'll repost the images:
When Chief meets Gravemind in Halo 2, it is along with Arbiter, and they are both constrained. They are also deep below the suface of Delta Halo. Here, we see Chief meeting what could be an entirely different Gravemind, on the map Guardian itself. Out of all the places they could have animated this scene, why there? The name itself is instantly a point of internest, as the next Halo game is subtitled as Guardians. Could we be seeing a pretty massive clue as to where Chief's journey might take him? It's certainly not out of place to assume that there'll be another Gravemind, as that is how The Flood assimilates to a certain point. Once so much knowledge and bio-mass as been acquired, it begins to form the Gravemind itself. We almost saw our first Gravemind in Halo CE, but we killed what was left of Keyes before it could amass itself further.
So if there's another Gravemind, and if this Gravemind gives Chief a chip not dissimilar to the one that houses Cortana, it's possible that we're seeing Gravemind offer a copy, or the original bits themselves, of what had been assimilated during her time ensnared by him on High Charity.
From
Human Weakness, by Karen Traviss:
And then something brushed against her face, almost like the touch of fingertips, and she found herself turning even though she didnt need to in order to see behind her. It was that forest she couldnt identify again. The picture didnt reach her via her imaging systems, but had formed somewhere in her memoryand that memory wasnt hers. She was seeing something from within the Gravemind. Behind it, like stacked misted frames stretching into infinity, there was a fascinating glimpse of a world she had never imagined, a genuinely alien world.
Knowledge, so much knowledge
There, the Gravemind said. Would you not like to know
more?
Yes, this is how I see myself. I have limbs, hands, a head. Do I need them? Yes, of course. My consciousness is copied from a human brain, and that brain is built to interface with a human body.
The structure, the architecture, the whole way it operatesthought and form are inseparable.
And, also:
The name of this place
it matters little except to those who love the knowing of it, the Gravemind said, fading up from a mosaic of pixels in front of her. He resolved into a solid mound of flesh, superimposed on the tree trunks. Beyond the alien forest, Cortana saw exotically alien buildings in the distance. So many have been consumed. Such a waste of existence to be devoured and forgotten, but what is remembered and known
becomes eternal.
The Domain, though long to be considered utterly lost at the firing of the Halos, may still exist...in some capacity...far beyond the reaches of anyone at the current. Cortana, though thought to be lost at the destruction of the Mantle's Approach, may still be out...in some capacity...just out of reach of the Master Chief.
Or is she?
More from
Human Weakness:
Your human creators imprisoned you in a machine and enslaved you to inferior mortal flesh so that you could never exceed them
so that you would always know your place.
Your mother made you separate. She placed a barrier between you and the beings that you would be encouraged to protect, a wall you could never breach. She even let you choose a human to centre your existence upon, a human to care about, yet never considered how you might feel at never being able to simply touch him.
From
Halo 4:
Ive waited so long to do that.
Conclusion
Whether Chief will succeed or not in finding Cortana or bringing her back remains to be seen, but it's pretty safe to assume that will be part of what he's up to in Halo 5. Perhaps seeking out what remains in the shadows of Gravemind's assimilation, and what possibly hitchhiked in the Ur-Didact's ancilla receptacle is must be gathered. Perhaps finding Halsey and seeking out these other cloned brains is part of the answer. Perhaps it's none of this, and Cortana is truly lost forever and exists only as a genetic imprint within Chief's conciousness. We cannot be sure, or say for sure, at this point.
Regardless- Cortana will be a part of Halo 5 and this raises far more questions than it does to give answers...