I've spent the past year assembling a list of rumoured leaks for Halo Infinite. Make of them what you will.

Take all of this information with a grain of salt. I am not the one responsible for this information, however I have spent a great deal of time inquiring with those who were given info from employed/formerly employed members of 343 Industries. I will delete this post if asked.

• Fall 2020 release window,
• Standard file size is 60GB, 4k uncompressed file size is potentially 120GB
• 3 separate campaigns: Master Chief, Locke, Jerome-092
• 2 separate multiplayers: Classic and New movement + Forge
• Modular installation method for all 6 features, no mention of Theatre mode afaik

Campaign: There are supposedly 32 missions in total so far, Halo Wars 2 and recent novels will tie into the campaigns in some way shape or form. Each campaign will have some relevance to one another – but they won't have a traditional linear narrative, with 343 expecting people to be confused by the approach of the story. It's implied that the main campaign (Master Chief's) is not the end of the story, and is continued via the others.

A test demo of one mission was made available to developers, where you play a level similar in nature to the Silent Cartographer - controlling Spartan Thorne (in what is implied to be part of Locke's campaign) you fight Elites that share both 343i and Bungie artstyles (343i Elites are heavy weapons/cannon fodder, Bungie Elites are Scouts, Leaders, etc).

Multiplayer: There is a Warzone-esque game mode, where you play as different classes such as Medic or Assassin - with the assassin having the ability to use active-camo. Sprint and thrusters are staying - but are heavily fine tuned and modified from their Halo 5 iterations. Spartan Charge/Ground Pound abilities have been removed, with no mention of hover. ADS is also still in, but more reminiscent of classic Halo zoom (certain weapons perform the binocular zoom from older games instead of aiming down sights).

Hitmarkers were present in test builds, but were disliked and either reworked or removed. There were also test builds containing wall-running on particular maps, but it's unknown if they are intended to be in the final product.

Customisation: The armor customisation is equal to Halo: Reach - with different equippable armor sets split across different eras from the games/books, unknown if the Credits currency system from Reach is in use. Black undersuits are in - with a functioning wear/tear system for armor as well as optional addons for plasma scarring, blood stains, etc. At most, there are said to be at least 18 sets of armor available at launch.

Certain armor permutations can only be unlocked through playing the game conventionally, while MTX variants can be bought and applied to existing armor (similar to the skin variants in Halo 5). There was an idea proposed that if you spend a particular amount of money on MTX, you are locked out from further purchases ranging from a week to a month long – it's unknown whether this feature will be present at final release.

Engine: The Slipspace engine is a heavily reworked and modified Blam! engine, and was not used for the 2018 E3 trailer. The 2018 E3 trailer was rendered using OctaneRender. The footage shown at E3 2019 is in-engine, and shows the opening cutscene of the game. Skybox Labs is working with 343i for the AI pathfinding in the game, while The Coalition has allowed 343 to incorporate their high definition audio engine for atmosphere, weapons, vehicles, etc.