Gosh why do they have two threads for this one topic? D: now i have to repost my previous ideas.... oh well... here are some thoughts me and my clan (Burning Wolves) came up with:
MORE ARMOR CUSTOMIZATION!!!!!!!!!!!!!!!!!!!
bullet time record in theater
lower weapon key on d-pad
drivable pelican in custom games and possibly multiplayer
ability to go prone
RVB firefight voices
special FX's nighttime and raining
gauss rifle (not the type twin reaper posted (btw i posted this idea way before him) mine is more...removed turret like than his sniper design (his design is nice but for a totally different weapon) and the battery life idea is not good with his since futuristic batteries should not be easily depletable even though its attached to a railgun...)(this weapons would be spartan useable only because of its size and kickback)
no item limit in forge
AI's in forge
weapons customization
warthog with flamethrower turret (increase range of the flame)
firefight voices usable in customs and multiplayer?
remove helmet option like in ODST
character (face appearance) customization
new building types, plates, and vehicles for forge (possibly scarab and pelican plz? it would make customs so much more fun and making movies so much easier)
better weapon sounds because the tiny buzz of the gatlin gun is so unrealistic compared to what it should sound like seeing as its firing several hundred rounds a minute
Key on the d-pad that allows melee weapons on ur armor to be pulled out and used in normal combat (plz have a katana!!!)
armor pieces give certain upgrades such as: shotgun wrist attachment allows for more shotgun shells carried when weilding a shotty, or a gps arm attachment comes with a small satalite map of the area with heat signitures of enemies, etc
armor effects SHOULD BE KEPT (unless u want to remove armor lock and jetpack then im not complaining since noobs use those a lot)(the one use armor effects of halo 3 should be brought back UNDER NO CIRCUMSTANCES)
props on the sprint always being inabled idea it will make games so much easier
armor effect that allows for automated turrets to be set up and for vehicles to be repaired (the vehicle repair one could just be a toolkit that the spartan uses near the engine of the vehicle)
interactive environment: doors that can be opened and closed for cover or for exiting into space environments and possible loadout items that involve various types of antipersonel mines and sticky explosives that are detonated by remote @w@
more realistic killzones (come on! spartans can breath for long periods of time in space but they cant go underwater???)
(personal note: i believe the dmr is much more efficient and accurate than the br and that the dmr should be kept and the br should be disposed of >.<) (though im sure ill recieve tons of hate mail to the opposite ideal)
(new idea!!!) agro system like army of two but more advanced so that whenever one of the players is firing in firefight or campaign and the other players arent firing the enemy will rush or shoot at that player (this would make things horribly realistic seeing as in rl when a group of soldiers has an enemy behind cover and one of them breaks cover and fires all fire is directed at that enemy to keep him down or kill him)