1. Revert the grenade throwing back to the original Halo trilogy
2. Promethean vehicles.
3. Have the Covenant speak English again......I miss listening to the grunts talk funny.
4. Bring Cortana back
5. Bring back the original plasma rifle. have both plasma rifles, just make the original one named "Plasma Rifle Mk I" and the new one "Plasma Rifle Mk II"
6. Bring back THE FLOOD
7. Bring back Firefight from Halo: ODST or at least make something similar to it like Horde mode in the Gears of War series.