I want the complete Halo experience with the new style Infinite is supposed to be providing.
I want the ranked playlists: 2v2 Team Slayer, 6 Player FFA Slayer, 4v4 Attrition, 4v4 Arena (King of the Hill, Oddball, Strongholds, Capture the Flag), 4v4 Team Slayer, Monthly/Seasonally rotating mode (4v4 Team Snipers, FFA Snipers, 1v1 Slayer, etc.)
I want the social party modes experiences: Team Snipers, Escalation Slayer (Gun Game), Grifball, Infection, Swords and Hammers, etc.
I want a Customs Browser to be able to join random games (social or competitive in nature) and to be able to easily host custom lobbies.
I want the Co-Op campaign and other fun co-op pve modes, eg. Firefight.
I want a sense of progression: Career Progression in the form of Halo Reach Inheritor ranks, SR152, anything really.
I want a sense of community in the game: File Share, Pregame Lobbies (With Map Veto, Game Chat and Party Up Features) and Detailed Service Records (showing ranked playlists ranks, career progression, campaign stats, multiplayer stats, game time, etc.) and be able to view other peoples Service Records with ease.
I want the events to feel like BIG things that I dont want to miss out on.
Christmas events for example could add a snowy aesthetic to maps, add christmas decorations to maps, weapons and armour, a new weird and wonderful event mode like a snowball fight mode or something.
I want to be rewarded for playing the game (and not in a very specific way ie. challenges). I want to complete a match and be rewarded for winning and for playing well.
I want aspirational achievements to aim for. Give us things like special armour for reaching Onyx rank, ranked nameplates, weapon coatings for completing challenges in a similar way to how Call of Duty has camo challenges for weapons.