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 has been rumoured for more than a year, having previously been called Project Yeti in many a rumour. It is a cloud gaming service whereby members can play any of the games available, but don't have to download them or purchase them individually.
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 it differs from other platforms, such as Nvidia GeForce Now and PlayStation Now, Stadia 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, etc. 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 (usually through Bluetooth or another wireless connection) 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 noggin.
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 recent 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 Chromecast plugged into a telly. We're also hoping it will work on iOS devices, but are yet to receive confirmation.
How much will it cost?
Although we have no idea of the payment system yet nor official word on cost, rumours point to Stadia being a paid subscription service - much like GeForce Now and PlayStation Now.
PlayStation Now, which is available through PS4 consoles, costs £12.99 a month. For that you get unlimited access to PS3 and PS4 games streamed over the 'net (plus some of the titles available for full download, to combat latency criticism).
Nvidia's GeForce Now is currently on free trial, thanks to an all-new beta testing phase, but was previously priced at £7.49 a month. For that, users got to play PC games run remotely on hardcore gaming PCs sporting top-end Nvidia graphics cards.
We'd expect Google's service to be priced nearer the latter.
What games will be on Stadia?
An actual games list is yet to be revealed but it is likely to host a wide selection of games.
The Project Stream trial, for example, was run in partnership with Ubisoft. Beta testers got to play the full version of Assassin's Creed: Odyssey, even up to 4K resolution if their bandwidth was good enough.
Also, during the GDC 2019 launch event, iD Software revealed that it is developing a Stadia version of Doom Eternal.
We expect the final service to offer similar triple-A games run at their best on impressive hardware.
What quality will games run at?
Google claims that, on launch, Stadia will be capable of running games in up to 4K HDR and at 60 frames-per-second. Of course, the quality of video you receive will depend on your own broadband connection and we're yet to hear what the minimum speeds will be for different video performance levels.
The Stadia servers - the hardware running the games - are higher specced than the PS4 Pro and Xbox One X, so they are very capable, but we suspect video performance will need to be scaled depending on your data speeds.
Google even makes a bold claim that, in 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 will Stadia be available?
Although we don't have an exact date, Stadia will be launched in the UK, US, Canada and Central Europe this year: 2019.
We might find out more in June during E3 2019 in Los Angeles.