Campaign:
-Cortana´s return (i dont know how but 343 could be creative maybe a real clone or another ai, 343 we could surprise)
-a more tactical chief (i think that can be a nice improvement a chief that can take cover, roll or be sneaky in some parts of the campaign could be awesome but not forget the essence of halo)
-epic quick time events (not basic time events, i think that was a nice add to the game but can be more epic with stunning animations and be part for the combat in some parts, but dont put much. and can be part of some bosses battles)
-Fauna (only in reach i see an animal that represents a "risk", i think could be awesome that strange animals or plants in the environment represents a risk, and the levels look with more life)
-unlockable side missions (side missions in the campaign that can be unlock if we make a specific thing in the game and tell us more about history, this mission could be playable with other characters, maybe elites, odst, our spartan or some enemy)
Multiplayer:
-Not only spartans (elites or some variant of promethean culd be fine or a new race)
-more armors and things to personalize our spartan/elite or another charcter
-a new games, that we have the option to select a specific class or race with specific abilities (sniper, heavy gunner, tactical, engineer and be like fortress defend or some game more tactical and use the specializations of halo 4, and has its counterpart , like hunter (heavygunner), jackals (sniper) improve defensense in the fortress and could call reinforcement (for example the covenant can calla scarab for a limited time) )
-spartan ops and fireflight (but please be more creative with spartan ops no only kill one million of enemies, maybe add space missions or something new to add variety of the game and not S.ops for only gold members xD.)
-Tribute for old maps (remake of old halo maps its funny and melancholic remeber old times with old maps)
Forge:
-a better custom forge (this forge be awesome, the lights and the assets, but please make more options, like select day/night, color map options, weather effects, environment assets like trees, rocks, flowers (details than can make a map unique) and a cinematic tool that let us make small mini intros for other kind games )
-Enemy Ai (put enemy ai be awesome, put flood or zombies ai or hunters and jackals snipers, suicide grunts would add more fun to the creation of maps)
-trigger assest ( like levators, or trigger doors, trigger zone to active a special thing (like a finish line for cars races xD))
-money in the game (gain money killing enemies and use to improve torrets or some thing (yes like gears of war xD))
basically things that let us create maps and a funny variants of games to pass the time with friends
*sorry for my bad english
