vehicle availability
i am not always the kind of guy that goes for the vehicles every game like some halo player, but when i have that urge to get in one w/ my friends in my party and just gun some people down until an enemy gets a triple kill, i find it hard to move 20 feet w/out hitting a bunker or broken parts in the road. i just wish there was enough open areas to drive the vehicles.
more guns
there are so few guns that i almost never feel a sense of accomplishment. what i mean by that is, it takes so long to rank up to lvl to get a new gun unlocked. i wish there where a larger list of guns so that you can get a new one at least every 5ish levels.
more attachments for shotguns and snipers
i mainly snipe. thats my thing. but of course there are just some maps where that is just not easy/fun to do and im not saying i dont like those maps. i like the variety of maps. im getting sidetracked though. when im sniping or shotgunning, there really aren't that many options to pick from when it comes to customization w/ attachments. i dont know who snipes w/ a reflex sight or who uses a silenced shot gun all THAT often. why not put in some more useful attachments like a bipod for snipers or grip, dual wield, or round drum clip for shotguns. i wish there where a lot more useful attachments for the snipers and shotguns.
(this one is not really for a DLC because that would be way to hard to do, i would imagine)
more customization of your character/soldier
i dont know if im the only one but i hate seeing 16 generic blue and orange guys fighting. i would like to be able to change the armor, helmet, pants, or even facial features. you make the soldier and then depending on what team you are, the colors of your armor are your teams colors. i wish you could create a custom character.