1. They NEED to have promethean and flood vehicles.
2. Have more than one campaign
a. spartans vs. flood
b. spartans and covenant vs. prometheans, spartans looking for Cortana
c. San'Shyuum, brutes, and spartans vs. flood, covenant, and prometheans
3. Be able to make firefight maps.
4. Add movable doors, buttons, levers, and infinite objects/budget to forge.
5. Bring back invasion, VIP, race, and firefight.
6. Add gamemodes like skirmish and pistol power where you only have pistols.
7. Include more original weapons.
8. Get rid of Master Chief and add the crimson team and creating your own full AI campaign squad that levels with you.
9. Make one HUGE forge world with different biomes to forge in.