It is effectively the company's "Netflix of games", with games hosted on remote servers and video streamed to connected devices, including smartphones, tablets, computers and TVs.
But what will Stadia offer? And how will it be different to existing cloud gaming services?
What is Google Stadia and how will it work?
Stadia was rumoured for more than a year, having previously been called Project Yeti. It is a cloud gaming service whereby games can be purchased and played, but don't have to be downloaded to a console or PC.
That's because, through multiple connected devices, including phones, tablets and/or TVs, you play the game in real time, but it's actually run on a remote Stadia server somewhere else in the world. The video of the gameplay is transmitted to your device over the internet, while the control codes from a game controller are sent in the other direction.
The biggest hurdle other similar services have encountered over the years is latency - the time it takes from the moment you move the controller thumbstick or press a button to the action occurring on screen.
But, where Stadia differs from other platforms, such as Nvidia GeForce Now and PlayStation Now, is that its servers are placed in a vast number of locations around the globe. That shortens the distance between player and a server to stream from.
In addition, Google has developed a dedicated Stadia controller that connects to the internet directly via Wi-Fi, rather than your device. That means it sends controller codes without having to submit them to your phone, tablet or other connected device first. That cuts down on milliseconds of latency and, in gaming, that really matters.
That's because, usually on a cloud gaming platform once you've pressed a button the signal has to be transmitted (most often through Bluetooth) to the receiving device, then sent over an internet connection. It is subsequently read by the source device, sent back to the receiving device, then transmitted to your TV (if not using a smartphone or tablet screen). Each of these actions take time and that can be vital to smooth gaming experiences as milliseconds can be the difference between avoiding a bullet or being shot in the face.
What devices will it be available for?
Previous rumours suggested that Google would launch its service with its own Made by Google games console. However, while that could still be the case one day, it doesn't actually need one as any connected device will do.
The company's 2018 Project Stream trials worked through the Google Chrome internet browser and so will Stadia. It will therefore be available on PC and Mac without extra dedicated software or devices.
It will also work through other connected devices: TVs, Android phones and tablets, as well as a Chromecast plugged into a telly. We're also hoping it will work on Apple iOS devices at some point, but are yet to receive confirmation.
In terms of specifics, Google has announced that its Pixel 3 range of smartphones will gain a Stadia application and be compatible from day one. That includes the Pixel 3, Pixel 3 XL, Pixel 3a and Pixel 3a XL.
How much will Stadia cost?
Google has announced that Stadia Pro membership will cost £8.99 per month in the UK, $9.99 per month in the US. That will give users up to 4K HDR gameplay. However, in contrary to previous reports, it won't give access to a library of games.
Instead, Stadia Pro membership will entitle users to play "roughly one free game per month". It is similar, therefore, to PlayStation Plus and Xbox Live Gold, rather than an all-you-can-eat subscription.
For early adopters, a Stadia Founder's Edition bundle is available for pre-order. Priced at £119 ($129) it includes a limited edition Stadia controller in "night blue", a Chromecast Ultra capable of streaming 4K HDR gameplay to your TV, three-months of Stadia Pro for you and a friend, plus one of the launch games, Destiny 2 and all of its expansions. You will also get to choose your unique Stadia username before many others join the platform.
A final option for Stadia access is to pay as you go only. Like Pro, Stadia Base membership means you have to buy games individually but you don't get any free games. Stadia Base is also restricted to a maximum of 1080p.
With both membership options, purchased games will forever be assigned to your Stadia account and you can play them as often as you like.
Pricing for new games will be determined by developers and publishers. As Stadia boss Phil Harrison told Eurogamer in June, they will be of equivalent cost to PS4 and Xbox One games: "I don't know why it would be cheaper," he said.
Separate Stadia controllers are available in Just Black, Clearly White and Wasabi colourways at £59 ($69) each.
What games will be on Stadia?
A full games list is yet to be revealed but several key titles are now known.
The Project Stream trial was run in partnership with Ubisoft, and has since confirmed that many of its titles will launch on the platform.
During E3 2019, several other publisher also announced that they will be supporting Stadia.
Here is the confirmed game list so far:
- Assassin's Creed: Odyssey
- Baldur's Gate III
- Borderlands 3
- Darksiders Genesis
- Destiny 2
- Doom Eternal
- Dragon Ball Xenoverse 2
- Farming Simulator 19
- Final Fantasy XV
- Football Manager 2020
- Get Packed
- Ghost Recon Breakpoint
- Just Dance 2020
- Marvel's Avengers
- Metro Exodus
- Mortal Kombat 11
- NBA 2K
- Power Rangers: Battle for the Grid
- Rage 2
- Rise of the Tomb Raider
- Samurai Shodown
- Shadow of the Tomb Raider
- The Crew 2
- The Division 2
- The Elder Scrolls Online
- Tomb Raider
- Trials Rising
- Watch Dogs Legion
- Wolfenstein: Youngblood
What quality will games run at and what broadband speeds will they require?
Google claims that Stadia will be capable of running games in up to 4K HDR and at 60 frames-per-second.
It is also capable in up to 5.1 surround sound. However, all video performance and sound quality will be determined by your broadband connection and require a Stadia Pro subscription (Stadia Base maxes at 1080p).
For the best experience - 4K HDR at 60fps and with 5.1 sound - you really need a recommended speed of 35Mbps. However, games will still run from a recommended, absolute minimum speed of 10Mbps. You will likely be restricted to 720p and stereo, but should still get 60fps.
You can check your speed using a dedicated online test here.
Google makes a bold claim that, sometime in the future, Stadia will be capable of streaming in up to 8K and at 120fps. However, that is a long way off and will require far greater internet speeds than many national averages.
When and where will Stadia be available?
Stadia will be available from November 2019 in the following countries: UK, US, Belgium, Canada, Denmark, Finland, France, Germany, Italy, Ireland, Netherlands, Norway, Spain and Sweden.
Google plans to expand the service to other countries and regions in 2020.