: How about going from ce to Halo 2? How did chief get back? Isn't Johnson
: dead? Wtf are these brutes? Buggers?

Chief was last seen at the end of the CE flying in a spaceship away from Halo. Presumably he flew home.

Johnson hangs a lampshade on the fact that he's still alive. The script literally makes a joke about it.

: Or Halo 2 to 3? Why is chief crashing to earth? Wasn't he on that ship? The
: hell happened there? How is the arbiter on earth? I thought grunts were
: with us now? Why are the brutes different?

"Chief jumped from the ship" is literally the first scene of the game. It's not mysterious at all.

The Arbiter flew back to Earth with Johnson and Keyes. It can be easily assumed based on what is shown.

: Halo reach to ce? Woah woah. Spartan 3s? Those aren't jackals... Brutes? But
: they weren't... Wat? Master chief never gets cortana in reach? Then how
: does he know her so well in ce?

I honestly don't follow you. Jackals looking slightly different is a much smaller change than "Chief has a family -- and humanity has additional saviors -- that no one ever mentioned".

: It's been like this for all the games. The gaps are terrible and filled
: poorly by other media. I always have to catch my vanilla Halo friends up
: each game. Yeah it sucks. Or you could just skim the other media. Cliff
: notes and wiki's do exist, ya know.

I've never been thrown by a gap between the Halo games like I was between Halo 3 and Halo 4, and Halo 4 and Halo 5.