What are some things you would like to see in the new game?
For me, i want them to bring back FireFight. the first time I played it in Halo ODST i didn't think it was very fun. but when Reach came out i enjoyed more because i could customize my enemy to make more epic battles. i used to turn on all the cheats in the options menu so i could kill hundreds of Elites all at the same time for the fun of it. I even made all the enemy waves 100% Hunters once to see how that would work out. one thing i think they could add is the option to deploy not only Covenant troops but also UNSC, Flood, and Prometheans into battle at the same time. that way if you got bored of fighting the Covenant or doing it by yourself. you can deploy other factions into battle to mix it up a little. heck, even choose to fight against the UNSC. or even make your own UNSC Vs Covenant or Flood Vs Prometheans battles. hell, deploy all 4 factions at the same time for complete chaos.
But that's just my opinion.