Release dates: September 23 (Early Access), September 27 (official release date), September 29 (Japan)
Release time: 12:01am Pacific - same moment worldwide (5pm Eastern Australia)
Platforms: Xbox One | Xbox One S | Windows 10 PCs
ESRB/PEGI: E for Everyone, PEGI 3
Kinect: not required, used for voice navigation
FPS/Resolution: 30fps 1080p (console) | unlocked to 4K (PC)
Wheel controllers: supported (list TBA)
Play Anywhere: Buy digital on Xbox to receive the PC version for no extra charge
Cross Save: one account, gamesave and Achievements and DLC work on both platforms
Cross Play: console players join PC players in online sessions
XBL Gold: required for console online, not required for PC online
Co-op: 4-player online campaign co-op for every solo event in the game, share cars
Online Adventure and Freeroam: 12-player racing
Playground Games: King, Infected, Flag Rush
Car Meets: included at airport, drag racing
Private session multiplayer: included
Split-screen: not featured
Clubs: included, 1000 players (see also Xbox Clubs)
Drivatars: multi-game system, start Convoys of 4, Hire/Fire friends
Editions: digital: Standard/Deluxe/Ultimate | Xbox disc: Standard softcase, Ultimate SteelBook
Pre-Order Bonuses: retailer/digital bonus DLC, diecast Centenario, FH2/FM6 DLC, Early Access
Loyalty Rewards: up to 12 gift cars for Forza Rewards & prior VIP/gameplay, no credits
DLC plan: VIP, All-Stars Car Pack, Car Pass, 6 monthly car packs of 7 cars (October-March)
Demo: Xbox One, 18GB, includes 2-12 person multiplayer
Achievements: 64 worth 1000gs, same and shared for console and PC with Play Anywhere
Cars: 356 announced + DLC + special Horizon Edition variants and unspecified awards
Types: Utes, Vans, 3-wheelers, Offroad Buggies, offroad racing trucks, GT racing (All-Stars Car Pack)
Barn Finds: included
Upgrades: new Widebody kits, new rims, hood blowers, custom License Plates, custom Horn sounds
Tuning: no new options
Auction House: included
Driver customization: 14 avatar options varied in ethnicity and gender
UGC import: import existing designs and tuning settings from FM6, FH2, FM5
Livery Editor: included
Storefronts: centralized for creator designs, vinyls, tuning setups, photos (file limit ?)
Forzavista: featured for all cars
Photo Mode: included
Drone Mode: capture videos in solo and multiplayer
Environment: Australia. 6 ecotypes including rain forest, desert, beach, urban (Surfer's Paradise)
Festival: Gain fans to unlock Festival Sites, build and expand sites
Blueprint: customize every event by car and weather/time
Rivals: included
PR Stunts: Speed Traps/Zones, Drift Zones, Danger Sign jumps
Skills points: included
Perks: included
Bucket List: included
Horizon Promo: included
Bonus Boards: included
Music: 8 stations with curated songs and DJ announcements
Groove: upload your own playlist with OneDrive and Groove Music (free)
Economy: CR and XP payouts from races, Prize Spins for leveling up, Drivatar and UGC payouts
In-app purchases: included (details TBA)
Forzathon: timed challenges to unlock cars and features (comedy horn sounds, etc)

CROSS-PLAY
Can Xbox players join PC players in multiplayer? Do I have a choice?
Yes. "Gamers on Xbox One and Windows 10 can now play select multiplayer games together. Gears of War 4, Forza Horizon 3, Sea of Thieves and Scalebound all support cross-play between Xbox One and Windows 10 PC"^ "If for whatever reason you don't want to play online with PC players, or with Xbox One players, you will have the option to filter matchmaking by platform, but of course we encourage everyone to have fun with the game with as many players as possible in Horizon 3 via Cross Play."

Do I need Xbox Live Gold for either Xbox or PC? Can I play offline?
Gold is required for console multiplayer features. "You don't need a Gold subscription to play any of the online modes on a PC.

PLAY ANYWHERE
How does Xbox Play Anywhere work?
When you buy an Xbox Play Anywhere digital game through the Xbox Store or the Windows Store [or via a digital code at participating retailers], it’s yours to play on both Xbox One and Windows 10 PC at no additional cost. To take advantage of Xbox Play Anywhere, you will need to have installed the Windows 10 Anniversary Edition update on your PC, as well as the latest update on your Xbox One console. Then, simply log into your Xbox Live/Microsoft account and your Xbox Play Anywhere games will be available to download.

Does Xbox Play Anywhere cost extra?
No, there is no additional cost for Xbox Play Anywhere. When you buy an Xbox Play Anywhere digital game, the ability to play on both Xbox One and Windows 10 PC is included at no additional charge.

Can I be signed into the same game on Xbox One and my Windows 10 PC?
At any single point in time, you may only sign into the game on one Xbox One console or one Windows 10 PC. You cannot be signed into the same game on both an Xbox One console and a Windows 10 PC at the same time.

Will my game progress be saved on both Xbox One and Windows 10 PCs?
Yes. When you play an Xbox Play Anywhere game, your game progress is saved on Xbox Live. So, you can pick up where you left off on another Xbox One or Windows 10 PC, bringing all your saves, game add-ons, and achievements with you.

Will downloadable content for Xbox Play Anywhere games also be playable on both Xbox One and Windows 10 PC?
Yes. Downloadable content that you buy or earn for an Xbox Play Anywhere game that you own will also be playable on both Xbox One and Windows 10 PC. This includes game add-ons, Season Passes, consumables and in-game unlocks.

Will I earn Gamerscore and Achievements twice if I play the game on both Xbox One and Windows 10 PC?
A single shared set of Gamerscore and Achievements will be earned and awarded for Xbox Play Anywhere games.

Can I give away my Play Anywhere PC copy or let others use it while I use the Xbox version?
No, the PC version is tied to your account, which can only be logged in one place at one time.

There are three Editions of FH3: Standard ($60), Deluxe ($80), and Ultimate ($100) available in two formats: digital (Xbox+PC, all three editions) and disc (Standard and Ultimate, Xbox only). The base game's content and roster of "over 350 cars" is the same for each Edition and both Xbox and PC versions, with the exception of a display settings menu for PC.

Deluxe includes Standard game plus the All-Stars Car Pack and VIP membership.

Ultimate includes the Deluxe list plus the Car Pass and Early Access.

Early Access is not available to add to Standard or Deluxe Editions.

Digital is the only way to get the Play Anywhere benefit (each Edition).

Xbox disc is available in softcase Standard Edition and Steelbook Ultimate Edition. There is no PC disc option

Select retailers are offering Pre-Order Bonuses (next post) including DLC and Forza-branded merchandise.

The "Ultimate" Edition does not guarantee "every add-on for FH3, ever" - the included Car Pass only covers regular monthly car packs through March, and past Forza games have released expansion DLC which cost extra for everyone. There may also be individual promotional DLC cars with third-party requirements that are not included with purchase of the three editions.