Halo 3 was a pretty fantastic way to bring the series "full circle" -- no pun intended -- and Bungie did it again with Halo Reach. I think we're all in agreement here.

Afterwards, Halo really struggled to establish a coherent narrative that spanned the games in the same way Halo 1 through 3 did. Looking backwards, Halo 4, 5, and Infinite seem very disjointed.

Something newer fans don't realize is that Halo is a spiritual successor to Marathon (and, for awhile, was possibly part of the same universe.) Halo's story is rooted in Marathon's.

What's under-appreciated is that Halo 4 built almost entirely on plotlines introduced during Bungie's tenure. It was a solid Halo game, and it was a very solid extension of Marathon's legacy. But I'd like to focus on how Halo 4 really does build on the Halo universe:

• Shield worlds were introduced in (very good) Halo: Ghosts of Onyx book, and we see one in Halo Wars. These were always pretty magical, cool, and under-explored, and going inside a shield world was one of the big "hype" things for Halo 4.

• Requiem specifically was introduced in Halo 3's legendary ending, and given its name later on in an art book released before Halo 4's announcement.

• Rampancy -- the condition Cortana is inflicted with -- was established in canon since Halo: The Fall of Reach, is a carryover from Marathon. I was pretty surprised when this took fans by surprise-- it's explicitly acknowledged in Halo 3's mission titles, and Cortana has shown signs of rampancy ever since Halo CE.

• The Librarian and the Didact were introduced in Halo 3's terminals, and were the subject of much discussion on the messageboards of the day. This was a huge amount of Forerunner exposition, and this was the first time we got dialogue from them. Greg Bear would blow open the Forerunner lore in his (excellent) book trilogy, but at this time, the Librarian and the Didact were huge bits of exposition.

• Halo 4 also started to answer a dozen dangling questions: Would there be Spartan IVs after the Spartan IIIs? What will fill the power vacuum of the Covenant? What about all the remaining Halo rings? What does a reclamation mean? What is the mantle of responsibility? Did any Forerunner survive? Did any Flood survive? What about precursors?

But more importantly, Halo 4 made some serious contributions to the aesthetic of Halo that we're now beginning to appreciate. I think the problem with Halo 4 is that people wanted the tone and aesthetic of the original trilogy, whereas 343i was looking at Reach and ODST and intentionally diverging.

Halo 4's soundtrack is fantastic on its own, but disappointing to someone who wanted more of the original trilogy. But it introduced instrumentation and riffs that are now an appreciated part of Halo Infinite's soundtrack. Master Chief's new design makes him look and sound and feel like a tank, but it alienated fans at the time. But that bulky and heavy presence is now an appreciated part of his Infinite armor, etc.

More improtantly, I think Halo 4 was the last Halo game that carried the underlying current of tragedy and sacrifice. Halo CE and Halo Reach have each mission being one step forward, two steps back, until a pyrrhic victory that falls far flat from the definition of success defined in the start.

With CE, you want to save the Autumn and gain control of the ring to defeat the Covenant. By the end, the Autumn and every single other ally is dead, you barely avoid galactic genocide, and you're no closer to defeating the Covenant.

With Reach, the goal is to drive the Covenant off Reach. Every victory in a mission is dwarfed by a Covenant success, until you die on a lost planet.

With Halo 4, the goal is to heal Cortana and defeat the Covenant faction. Along the way, you awaken the Didact, who finds Earth within days (something that took the Covenant years). You fail to stop the Didact, you fail to keep the Composer on Ivanoff station, you fail to prevent the Didact from firing on Earth, and you even fail to save Cortana.

(Just like Reach, if you read the books, then from the beginning, you know the end-- there is no cure for rampancy.) (Halo 4's story also closely parallels CE's, but that's another post.)

My main point is this: There is so much good in Halo 4. It suffered from the limitations of the Xbox 360, and it suffered from 343i's course-correction with Halo 5. If Halo Studios plans to remake the classic Halo games and reboot the plot afterwards, I really hope they include Halo 4.

TLDR: "Classic Halo" is Halo 1, Halo 2, Halo 3, ODST, Reach, and Halo 4. I hope Halo 4 gets the remake treatment and is included in the 'remake' timeline.