So I really like the idea of “untouched” multiplayer for each game, but at the same time I think they could add or change some things that would be universally loved.
For example, we all know zombies started in Halo 2 and back then it played a little differently. The “infected” had to actually change teams manually and they had the same weapons as the humans. This could lead to some jerks ruining the game by just shooting the humans with the pistol/shotgun they spawned with instead of using their sword like they were supposed to. I for one would love to see the updated version of zombies, at least how you automatically became infected once you died as a human. There will be no zombies playlist unless this is implemented.
There are other things like adding more custom game options, adding forge, theater, file sharing, etc…
Really all I need is H2 how it was in its prime, but things like the above would only add to the experience.