Love the gameplay of Infinite. I would genuinely say it has my favourite gameplay of the series. But besides that it really does fall behind the other Halos. Here is everything I can think of that Infinite desperately needs to become a GREAT Halo experience (aside from performance fixes like desync, crashing, etc.):
One thing before I start: you shouldnt need to sign in to an online profile to play the game splitscreen. Let my friend use a guest account. And local Custom Games should be fully accessible without an internet connection. I know nowadays its unlikely you wont have access to WiFi but its still important to accomodate for those who want to play some splitscreen custom games and DONT have access to WiFi at that moment in time.
Campaign:
Mission Select - Open World gameplay can be fun but a lot of people (myself included) would like the ability to choose missions and skip past open world stuff to the actual missions of the campaign in both solo and especially for co-op. Maybe all missions should have a fast travel option that immediately launches you to the beginning of the actual mission part of the gameplay?
Co-Op - Goes without saying network and splitscreen co-op are a necessity.
Co-Op PvE mode:
A Co-Op/Solo PvE mode separate to the campaign would be a great addition. Something like an updated/modernized Firefight would be great as something fun to do that isnt a campaign mission and is replayable. A good starting point could be using the House of Reckoning to create a dedicated wave based PvE arena.
Multiplayer:
Ranked Playlists:
6 Player FFA Slayer
2v2 Team Slayer
4v4 Arena (Oddball, Strongholds, King of the Hill, Capture the Flag)
4v4 Team Slayer
4v4 Attrition
Monthly Rotating Playlist (4v4 BR SWAT, 1v1 Slayer, FFA Snipers, 4v4 Snipers, etc.)
Missing Gamemodes:
Infection (An experimental Infinite modern version could be Survivors get a Bulldog, Sidekick, Shields and Repulsor; Infected have no shields, energy swords and grapple. Could be interesting?)
Grifball
Escalation Slayer (Gun Game)
Customs Browser:
This is the lifeblood of Halo and offers SO much replayability. This should be a priority as it allows players to host whatever they want for friends or find friends. And it allows people to find whatever they want, so they dont have to rely on the Social Playlists.
Team Snipers:
This mode needs fixing. There is no reason a Team snipers mode should have launched with non sniper weapons in it. It needs to be one of 2 things: S7 Sniper only or S7 Sniper + Shock Rifle only. No grenades. No power equipment or weapons spawn. Normal equipment can spawn.
Service Record:
This is important as it allows you to show off and track your progress in game. It should show your campaign stats (highest difficulty fully completed, missions completed, game time, etc.), possible separate pve mode stats, multiplayer stats (playtime, overall K/D, games played, specific playlist K/D and ranks, etc.) and overall stats (account level, overall playtime, battle pass progression, etc.)
Progression systems:
The game needs a passive overall progression XP system. It should provide rewards for milestones and maybe give challenge swaps, xp boosts, etc. for levelling up.
Social lobby features:
Would be good to see more interactivity return to the pregame lobbies. A map veto system would be nice, aswell as party up.
Theres likely even more that I have missed but I am confident once all this is added and fixes to performance, progression, ranking systems etc. are implemented then the game will flourish.