- Modding tools (better than Custom Edition's) (maps, gametypes, weapons, Campaigns, Firefights, etc).
- Bot practice mode
- Highly customisable Firefight.
- Downloadable Campaign packs (like Spartan Ops, but with Campaign missions that tell good stories that run parallel to the regular Campaign, or that tell stories from across the Halo mythos).
- Good AI.
- Two species with customisable armour (Elites and Spartans) and several models to choose from for other species (playable in customs and custom Firefight/Campaigns).
- Large varied sandbox.
- Campaign and Firefight scoring similar to the Skillshot system in Bulletstorm (to encourage players to play in different ways).
- Lots of unique skulls (that are found in Campaign, not unlocked automatically)
- Every vehicle, weapon, Armour Ability (only in customs and a playlist or two), Equipment, etc.
- Have a Kickstarter-like system for modders to fund their projects (with a percentage going towards 343/MS, of course

), and let people donate money to modders.
- Stats API (RIP in peace HaloCharts).
- Theatre for every mode (and free rendering!).
- Skillbased ranking system.
- Custom game browser.
- Work with people from the competitive community to create amazing and skillful gametypes that launch with the game.
- Have playlists for popular gametypes/maps/etc from the community.
- Large scale battles (up to 128 players).
- Maps with buttons and stuff that can be activated to alter the map or cause an event.
- A map/gametype similar to Sandtrap, but with giant warships (Super Invasion!). Instead of Ordnance, have an Armoury where you can redeem points for weapons and shit and customise their weapons and shit. Also, have a Commander that pilots the ship and does stuff like activate the turrets and closing doors and shit. Also squads.
- Gametypes with tiers (like Invasion).
- Good easter eggs.
- Pretty water.
- Let us see our health (like in Reach, even if we won't need to in most gametypes).
- Good UI (more like Reach, less like 4).
- Ability to customise vehicle weapons (Flamethrower Hornet, Shotgun Hog, Chain gun Ghost, etc).
I'll edit this post with more stuff if I can think of it.