Okay ive been thinking about this all day and some might not be so good but you decide
Heres some stuff that might help or be fun in Halo 4
First of all take out armor abilities change them to pick-ups/power-ups only have Holagram Jet pack active camo and spartans will all have sprint and if elites are in multiplayer the will start with evade.
First person vehicle driving- 343i should make you to be able to enable/disable first person vehicle driving and with first person deaths.
Ranking and armor- Ranking should be the same in Halo 3 but armor should be unlocked by ranking up, completing campaign levels, challenges ect. after you unlock the armor you have to buy it using the halo reach credit system.
Silencers- I know some people wont like this but i think it would be fun, you could enable silencers with some weapons or all in custom games, there could be a new upgraded invasion where it could be a stealth mission or something and when you shoot with a silencer you wouldn’t be on the radar.
SMG- Okay the SMG should come back definitely the one in ODST is really fun to use and looks awesome.
BR- Keep the DMR but bring back the BR
Longer campaign- There should be a Longer harder more action-packed campaign with a good story, there should be real stealth missions instead of just assassinating the first enemy then alerting the rest, where you would need a silencer a strategy and skill to complete it.
Assassinations- Keep the assassinations there awesome fun and cool to watch, maybe a few more though.
Dieing in a vehicle- I saw this in another post but when you die in a vehicle instead of just flying out of it randomly your body should stay in it and the next person to enter the vehicle would have to pull your body out if would to the same amount of time but it would be more realistic.
Armor Damage- When taking damage your armor should turn weathered and weaken your full shields
Or when you kill someone with a headshot their visor should crack
Infection upgrade- The zombies in infection should look like flood and there should be special maps for infection only.
New map pack- Kinda off topic but there should be a map pack called Memories or something with a ton of remakes of past maps from other halo games.