The ranks should be like standard military ranks, and when you reach a certain rank, you could get a ship(friget, or covenant ships) and be captain of that ship. It would be like a clan to where people could join, and you could also have computers playing(exp:marines) You could play as the humans or covenant. When you join one team(humans,covenant) you stay as that species,but you can join the other team and betray your own species(like the Arbiter). It would be a gametype a lot like Spartan Ops, There would be planets that you could invade and take over and own. You could orbit that planet as long as you wanted, but you could also just go through space. I have a lot more ideas, so if you would like to hear them, post a reply.