Let Me get this out there. I DON’T WANT THE CAMPAIGN TO BE THIS! THE CAMPAIGN SHOULD BE A HALO CAMPAIGN!
I will also say that I am assuming Halo 5 style Gameplay. That being said the Normal MP doesn’t have to play anything like this and this mode isn’t dependent on those mechanics either. They just make it better in my opinion.
All that out of the way let’s get started.
The Mode itself will be something of a fusion of Halo 4 Spartan ops, Halo 5 Warzone, and Destiny. You will be your Spartan and Start off on the Infinity, this can just be a menu or a hub it doesn’t really matter. From here you can alter you Spartan’s armor, Upgrades, equipment, and add, search for, or remove squamates.
You can then pick missions. These can be anything from daily, weekly, or monthly objectives, environment free roam, or storyline missions. After You have picked you will be taken to one of a variety locations with similar scale to campaign missions. You will be dropped in similarly to warzone, AKA pelican Drops or ODST drop pods. Once you are there you can do whatever you want but if you pick one of the missions there will be given a waypoint telling you where to go to start said mission. Some mission can be done alone, some should be done with a squad, and some will match you with 8 or more other players once you reach the location.
In these environments you will come across Enemies and ally AIs. You can choose to Kill the enemies or help the allies to get Points(Req Points/credits/money) that you can use to Upgrade your armor, get better weapons, get cosmetic items, ect but not enough that farming would be a viable option. Doing missions will get you much more of these points. Enemies will also drop weapons or be in vehicles that you can procure for your usage. Around the map you will find weapons cases(Downed Pelicans, drop pods, or UNSC bunkers) that act as Req station. You can use these to replenish your ammo, change you loadout, or even call in vehicles. Completing storyline missions will contribute to your armors power capabilities.
Increasing your Armors power will increase the number of perks you can use and unlock with point. Possible perk could be:
Shield strength: +20%, +40%, +60%, +80%, +100%(these wont stack but to use more powerful ones you much have the weak ones before it selected as well.)
Armor Strength: +20%, +40%, +60%, +80%, +100%
Shield recharger: -10%, -20%, -30%, -40%
Melee Power: +20%, +40%, +60%, +80%, +100%
Movement Speed: +10%, +20%, +30%, +40%
Thruster recharge: -10%, -20%, -30%, -40%
Double Thrust: Use thruster twice before recharge.
Stabilizer Strength?: Allows you to stay in the air longer and maybe able to move around faster.
Double Jump?
Patrol Case: Increase the amount of ammo you can hold.
Grenadier: increase the number of grenades you can hold.
Advanced Sensors: increase radar range.
Wheelman: Increases the durability of the game’s vehicles in multiplayer and reduces the time that they are disabled when affected by Plasma Pistol bolts.
Restoration drone: Vehicles are repaired overtime While being driving(doesn’t stack with multiple players)
Extra weapon: The ability to hold a third weapon.
There could also be armor abilities that you can select and upgrade.
There could be many others as well.
You will only be able to change these On Infinity. You can not change them in a mission.
The amount of Armor Power you Get after the first mission will be 2(2 points to put in any of these) and could get up to 20 maybe higher depending on the number of perks and how powerful they are. The amount of power you get per mission could be less or more. The Amount of perks active will also tell you your ranking. Someone with 0 perks will be rank 0 and one with 4 will be rank 1. Missions will also have this ranking and it will indicate the difficulty. To someone who is rank 0, a rank 4 mission would be seen as more difficult than Legendary for them.
Weapons could have attachment perks like the ones seen in Warzone.
Extended mag
Recon Scope
Longshot sight
Kinetic Bolts
Silencer
Stabilizers
Energy Bayonet
Knight Blade
Ect
Some of these can work with others and some can’t. I’d say you could have 3 or 4 at most on one gun.
The overall Story would be similar to Spartan ops. It would be what the Spartans 4s and infinity are doing during, after, or before the main Campaign. The Infinity is shipping off Spartan 4s to a multitude of colonies and alien planets to fight against the Created(They would probably be a combination of Prometheans and Covenant species), Banished, and or other Covenant factions. The Infinity itself won’t be able to give direct support as the possibility of losing it is to high a risk.