I've said it before and I'll keep saying it: 343 has yet to launch a game that's complete on release date.

• Halo 4 had no file browser and Spartan Ops was released over the period of the first 6 months (or year? I don't fully remember). Multiplayer also lacked commonplace Halo features, such as the red X that marks where you died to your team mates. They also scrapped modes like Firefight that Bungie had made standard modes in their prior two releases (ODST and Reach), and classic modes like Oddball weren't added until well over a year later. Theater was included, but only worked in Multiplayer. They scrapped usage in Campaign.

• Halo: MCC launched with multiplayer that was essentially unplayable until 6 months in, and even then it was rocky until 4 years later when, in 2018, they finally went back to fix the game. Halo 3 ODST came to the collection 6 months later as an apology, but only had Campaign (no Firefight like ODST launched with originally)

• Halo 5 launched with only 3 Arena modes and Warzone. Forge didn't come out until a month or two later, and Theater mode was broken (From my own experience, Theater will still randomly jump to a random player when watching films after a minute or so, although it's better than it was at launch, but still also only worked in Warzone or MP, not in Campaign). There was no Big Team Battle, debatably the most iconic Halo mode, which meant no vehicles were featured in matchmaking for a few months after launch. They also didn't add iconic weapons like the Gravity Hammer for months, which meant classic game modes like Grifball were not able to be played until the Grav Hammer released the next spring. They eventually added their own variation of Firefight, but it's only in Matchmaking and 5 waves. They added some impressive Forge-made BTB maps, but still no developer made BTB maps, which meant spawns can get pretty awful on user-made maps.

In comparison:

• Halo Reach launched with Slayer, Oddball, King of the Hill, Territories, Stockpile, Capture the Flag, Headhunter, and Juggernaut for Arena, had fully featured Big Team Battle maps, full Firefight mode with insane customization down to the enemies that spawned per round, a new and improved Forge with levels as impressively huge as Forge World, Theater mode (which worked in Campaign, MP, Firefight, and Forge), as well as a File Browser and fileshare system which allowed users to store up to 1,000 custom items. For reference, Master Chief Collection (with Reach, H2A, H3, and H4 allowing custom content) allows only 50 items still.

They need to launch a complete game. Halo 5 eventually got patched to be pretty solid, but the player base left long before. Bungie set the bar really high, and despite their rocky code, they created great experiences with lots of ways to play. I'm a little shocked that a 5 year time span to develop this game has lead to a delay, but 343 and MS both know this is becoming Halo's last chance to get big outside of the classic games.

EDITED to fix a mishap I wrote in on MCC instead of Halo 4