New Features and Updates:

Infection mode and playlist added.
New Arena map added: Stasis.
Added matchmaking preference options (Balanced, Focused, and Expanded).
Revamped Post Game Carnage Report.
Added Material Override and Texture Overlay options to Forge.
Increased value of Gold and Silver REQ Packs. (See below for details)

Multiplayer:

Fixed an issue that caused player properties to not be applied to players correctly.
Fixed a performance issue in Warzone caused by firing a Gungoose against a specific surface.
Brute Plasma Rifle added to Fiesta Classic.
Fixed a rare case that allowed a Spartan to spawn in the scope of an enemy sniper.
Reduced instances where players could spawn outside of the playable map area in Warzone.
Players can no longer knock teammates out of the REQ Terminal menus.
Fixed voice over for SPNKr and Weapon Pad events.
Public API: Fixed PlayerScore in MatchEnd telemetry.
Fixed an issue where audio didn’t play after finishing a Warzone match on Skirmish at Darkstar.
Round Based FFA modes now use total score to determine winners.
Custom Games Settings tweaks:
Players can now enable or disable weapon pickup in player traits.
Brute Plasma Rifle can now be selected as a loadout weapon.
Players can now adjust total rounds for magazine based loadout weapons.
Active Camo can now be set as a percentage instead of just on/off.
Moved Machinima Settings in the Custom Games UI to the General Settings submenu.

REQ System:

Increased value of Gold and Silver REQ Packs
First two slots no longer grant emblems, thus chances of receiving other permanent REQs such as power Weapon Certifications, Weapon Skins, Armors, and others has substantially improved if available.
Third slot now offers a large chance of awarding an emblem as well as a single use REQ
In general, the chance of dropping rarer single use REQs has increased.
Memories of Reach REQ pack available later today, for a limited time.

User Interface:

Added Matchmaking Search Preferences: Screen capture.
Balanced (default): Search for a match based on your fireteam's skill and network connection quality.
Expanded: Widen search parameters to find the first available match with reasonable skill matching and network connection quality.
Focused: Narrow search to find the best match based on your fireteam's skill and connection. Search times may be longer than normal.
Added a new recap screen in the Carnage Report. This screen lists each player's Medals, Tool of Destruction, who they killed the most, who killed them the most, and other match specific information. Access this screen by pushing "A" on a player while in the Carnage Report.
Added advanced options for vertical and horizontal controller sensitivity.
Added the ability to use Left and Right trigger to quickly navigate to other player's while on the recap screen.
Accessing Player Options in the Carnage Report now moved to the "X" button. Filter Team functionality (formerly the "X" button) has been removed from the Carnage Report.
Added the ability to see other Spartan's stances in the Carnage Report.
Added new celebration moment for a Spartan Rank up and a Competitive Skill Rank (CSR) up in the Carnage Report.
Changed the flow of the Carnage Report screens to start on the Match Stats screen first.
Added support for Infection to the scoreboard. Zombies and Alpha Zombies each display a new Infection-only graphic in place of their emblem.
Added the ability to rotate other Spartan's in the Carnage Report.
Added medal rarities in the Carnage Report to help highlight Rare and Legendary medals.
Added an Open Packs animation and pack count notification to the Help Bar if you have available packs to open.
Continued performance optimizations to the Warzone Terminal.

Sandbox:

Fixed a bug where Spartan Charge would not properly target enemies at the edges of red reticle on the horizontal plane (you can still get red reticle and miss vertically).
A target that uses thrusters will still escape.
Slightly increased movement speed while crouching.
Raised biped collision damage, making it easier to run over Spartans with vehicles.
Speedboost:
Removed shields recharging while sprinting while speed boost is active.
Performing a Spartan Charge against an enemy while Speed Boost is active no longer kills in 1 hit.
Plasma Caster: Default
Reduced non-charged timer from 0.5 to 0.3 (less overshooting of enemies).
Sticky grenade has less arc (to be able to place it on the map more reliably).
Sticky grenade detonation is now more damaging vs. vehicles, but less damaging vs bipeds (will still kill bipeds in one shot when stuck).
Increased sticky grenade submunition damage values from 43 to 75 (indirect fire from a sticky shot can now actually kill!)
Sticky submunition grenade inner AOE increased from 0.65 to 1.0.
Plasma Caster: White Scar
Needles have improved aim toward nearby targets.
Plasma Caster: Scourge of Fire
Sticky shot now has 7 submunitions instead of 5.
Hydra Launcher: Default
Reduced recoil in hip.
Increased inner AOE radius from 0.4 to 0.8.
Increased impact damage to make it more effective against vehicles (still two rockets to kill Spartan).
Hydra Launcher: Typhon
Enabled multi lock on for up to 3 targets.
Increased impact damage (still two rockets to kill Spartan).
Scattershot: Loathsome Thing
Increased number of hardlight projectiles to be same as normal scattershot (5 -> 8).
Rocket Launcher: High Five
Increased AOE radius on cluster rockets.
Binary Rifle: Twin Jewels of Maethrillian
Reduced recoil.
Placed twin projectiles a bit closer together for easier biped targeting.
Covenant Carbine: Rain of Oblivion
Reduced recoil.
Increased zoom magnification a bit (closer to default Carbine).
Incineration Cannon: River of Light
Added slight homing to charge shot to hit multiple bipeds easier.
Incineration Cannon: Heartseeker
Added proximity detonation to charge shot (like the normal Incineration Cannon has) to make it more effective against airborne targets or targets behind cover.
Fuel Rod Cannon: Pool of Radiance
Fixed a damage bug (was not causing AOE damage on initial explosion).
Made projectile thicker.
Needler: Talon of the Lost
Reduced supercombine count to be same as normal Needler.
Needles have longer lifetime to more easily supercombines against difficult to hit targets (8s instead of 4s).
Spartan Laser: Selene’s Lance
Reduced recoil.
Made beam thicker .
Gravity Hammer
Spartan Charge with the Gravity Hammer is no longer one shot kill when hitting from the front.

Campaign:

Please note that enemy-specific changes will also apply to Warzone AI.

Reduced two-player difficult slightly.
Increased single player difficult slightly.
Made Warden attacks a little easier to dodge, particularly on lower difficulties.
Face Beam tracks moving targets less accurately
Gravity Bomb has less homing.
Melee attack has slightly less range.
Made the Warden slightly easier to kill from the front.
Reduced AI Focus Turret damage output.
Reduced AI Storm Rifle, Suppressor, and Light Rifle effectiveness.
AI Storm Rifle: fires in shorter bursts, projectiles spread out more and move more slowly. Jackals are now less effective than Elites with the Storm Rifle.
AI Suppressor: fires in longer bursts, projectiles have less homing. Crawlers are now less effective than Soldiers with the Suppressor.
AI now fire shorter bursts with the Light Rifle.
Increased AI Plasma Pistol, Needler, and Beam Rifle effectiveness.
AI Plasma Pistol: slightly higher accuracy and damage.
AI Needler: AI now fire longer bursts (i.e. can now supercombine players on Heroic and above), slightly higher damage.
AI Beam Rifle: slightly more damage (mostly this will make it a two-shot kill instead of a three-shot kill in Heroic single player, allowing Jackal Snipers to actually kill a player from time to time).
Added a "tackle" animation to Sword Elites.
Instead of stopping to swing at a moving target they can swing on the move.
Increased Elite, Elite Officer, and Solider Officer durability.
Reduced Solider bamf frequency.
Killing a Crawler now deals area-of-effect damage to all nearby enemies, softening them up or killing them outright.
Reduced frequency of Squad AI getting killed while in a gunner's turret in a player's vehicle.
Made being killed by an attached Plasma Grenade non-revivable, similar to lethal damage from a Binary Rifle.
Increased AI special ability chance with higher player count in co-op games, e.g. Plasma Pistol overcharge, grenade throw.
Increased AI promotion chancde with player count in co-op games.
i.e. in cooperative games you will enounter more high-ranked enemies where promotion paths exist (most noticeable with Grunts, Elites, Jackals, and Crawlers).
The first player to press the "Call for Help" now has priority, other players will have to wait their turn for a revive.

Forge:

New and updated features:

Material Base: Change the material of the primitive building blocks (blocks, triangles, cylinders, & rings). Choose from:
Default Metal.
Concrete.
Wood.
Covenant.
Forerunner.
Marble.