If I could add anything...

Games Halo 5: Guardians
1

It would be Guardian from Halo 3. The gameplay of H5G was new (yet familiar), and I believe that Guardian would lend itself well to the movement system in place for H5G. With so much flow towards the center of the map, and so many jump tricks to get vertical in gameplay, Guardian may just help more than a normal remaster would.

While I thoroughly enjoyed the beta, and have may fair share of fun, there are still issues to be dealt with.

2

being able to play as a marine.
ever since halo 3 came out, i remember in 2007 i always wanted a gamemode were you play as a marine on multiplayer.

you know like, you die pretty quick, you dont jump high, no shields ect

that would be pretty cool