Honestly, Reach’s campaign didn’t suck me in the same way that the prior episodes of the game did.
I totally understand it’ll never happen, but I guess if I had to ask for some all-time DLC though, I’d love to see Halo: Combat Evolved more fleshed out. By that, I mean I’d love several branching missions that expand on what we see the human characters going through. Among others, I’d love some Captain Keyes missions, such as the evacuation of The Pillar of Autumn with his command staff, clips of his capture and torture at the hands of the Covenant, and especially, his doomed expedition into the swamps that were so intriguingly shown to us in 343 Guilty Spark.
Also, I’d love me some Foehammer missions. Piloting her Pelican off of the Pillar, scouting for crashed marines, piloting the Chief around, supporting pitched battles between the marines and the Covies with Warthog and Scorpion drops as well as squad insertions, it’d be cool to me personally.
Past that, maybe some missions to bring a grimmer sort of look to an already grim game. A brief mission as the squad of humans that die at the end of the The Silent Cartographer mission, sacrificing their lives to buy the Chief precious time to continue his mission is one I’d like. Also, maybe a mission that gives a peripheral view to one of the biggest “battles” of the game, the Assault on the Control Room, but played with different goals, from a human viewpoint, simply trying to push the Covenant out of the valley to give the Chief a path to the objective.
For some Flood incorporation into this “pretend DLC”, one missions I would absolutely love to see is that of Staff Sgt. Marvin Mobuto. In the canon, he was technically the first Reclaimer, and as a human, he pushed himself in a futile quest through most of the Library, something like that would be interesting to play out, a violent, bloody struggle of surviving and killing as long and as far as possible.
Like I said, I was just spouting out random things I’d love to see in a Halo remake or DLC, but that I know will never happen.