I came up with this list a couple months ago. Enjoy:
A fighters minigame (i dont know, why not?)
a halo wars type gamemode where you fight with your troops
more weapon specific assasinations (using a grav hammer in an -Yoink- if u have one)
personal ordnance should land where you aim
return of: needle rifle, sentinel beam, plasma rifle, firebomb grenade,
new: bow, brute rifle, throwing knives, shock grenade
speed boosts allow wall running like in titanfall
knife customization (which knife design you choose and where it appears on your spartan.
fully customizable spartans and elites
make your own spartan ops (see post:LEVEL CREATOR PLEASE READ)
flood mode similar to cod’s extinction
Oakley’s forge ideas (youtube.com/user/thehaloforgeepidemic. just search for oakleys forge wishlist)
remastered older soundtracks
pulse grenades block bullets and pull people toward them.
all emblems and visor colors are unlocked at the start
allow weapon skin packs with new sounds and animations and more greatly changed appearances
choose personal ordinance or set it to random
levels of tac packs and sup ups (tactical packages and support upgrades)
accesories like attenaes, cloaks, feathers, or unusable knives for armor
no more glowing armor
more reach armor returns
fire doesn’t hinder movement
scattershot bounces more
roll or sprint, select in loadout.
the promethean turret should be detachable
misc firefight voices (girl;confident, boy;funny) that carry into everything (spartan death cries and grunts)
specialization commendations and challenges
better quicktime events and more of them
dual wielding better return if you are bringing back the smg!!!
harder to jump over ghost’s splatter
forge world returns, but with more varied environments
jetpack should look cooler
name your custom game loadouts instead of picking from a list
an elite cyborg would be badass
invasion where elites defend a scarab
bruteshot returns with half the strike distance of an energy sword
theatre: slow and fast mo recordings
So that was the list. Be sure to check out my other post on how much a level creator would benefit halo!