1) Add in a few more lines of dialogue to allow for better understanding of the story for newcomers. Seriously, all it would take to clear up the Storm Covenant is (In the cutscene where Chief first meets Del Rio and is told of the Infinity's purpose): "What are the Covenant doing here?" "They're a rogue faction Chief. They call themselves the Storm, and they still follow the Prophet doctrine." Don't get me wrong, I still think the story of 4 is by far the best of the series and one of the best in any recent FPS, but a little extra dialogue would have been enough to clear up half of everybody's problems with the story. 2) Completely redo half the level design in the game. Stop with this Halo 2/3/Reach lack of player choice and sandbox elements bullsh1t. Give me the open, airy fields of CE where I can setup battles like the Rockslide megabattle, or the Twin Bridges megabattle. 3) Completely redo the Covenant AI. I like the Promethean's chaotic approach to the battlefield (though that could still be greatly improved), but the Covenant are at their (excluding lolwallhackauotaimconcussionriflespam Reach) absolute worst. Make them reactive again, bring back roaming from CE, widen the variance gap (i.e. make Zealots ACT like Zealots, minors ACT like minors, etc.)