Possibility of FireFight on Custom stages in which case covenant can get through teleporters. FireFight with CPU allies such as the Master Chief, Sgt. Johnson, Spartan 1337 or Noble Team. Elite Honour Guard Armor and Arbiter Armor. Brutes as playable and can roar at stuff (I want to be able to roar at stuff because I want to roar at a turret.) A Flood-based firefight/infection game. A campaign mode for elites/brutes.UNLOCKABLE KATANA ON REACH!
These are just what me and a few of my personal friends would look for in a truly awesome game of Halo.
[Edited on 01.23.2011 1:36 PM PST]