The service lets you access a library of Xbox 360 and Xbox One games, even letting you download them to play offline. But unlike PlayStation Now, Xbox Game Pass features first-party games like State of Decay 2, Sea of Thieves and Crackdown 3 as soon as they're released.
Read on to find out about the pricing, features, and which games are on offer.
What is the Xbox Game Pass?
Simply put, it's a monthly subscription service that gives you access to an extensive library of Xbox One and Xbox 360 games, all playable on your Xbox One console or PC.
It's similar to Sony's rival PlayStation Now platform, but unlike PS Now, you don't stream the games - instead you have to download and install any that you want to play.
The downside is that you need to have enough hard drive space to install them, and will always need to wait for downloads before you can play, but the upshot is no worrying about streaming lag or connectivity issues. Microsoft is fixing that issue though; at E3 2018, the firm announced FastStart.
FastStart applies machine learning to download the necessary parts of the game first, unlike the Ready to Start system that developers manually configure. This means that downloads will likely be cut in half, and while it's currently only available with "select" titles, the good news is that it'll roll out in more languages and to games not part of the Games Pass in future.
Microsoft has also said that there is no limit on the number of games that you can install at any given time, and you can play downloaded games offline for up to 30 days.
There should be over 100 games on the platform at any given time, drawn from both the Xbox One and Xbox 360 back catalogues, but the library regularly rotates, with new games added each month and others taken away. Once games leave Xbox Game Pass you can't play them any more, but your progress and achievements will be saved.
As mentioned above, if you fall in love with a title you can choose to buy it so that you own it permanently, and you'll get a 20 percent discount, along with 10 percent off any DLC - but only if you make the purchase before the game leaves Game Pass, and only if it's an Xbox One game.
It's worth noting that while Xbox 360 games are included in the service, Game Pass itself is only available on the Xbox One, and not the older console.
Finally, you don't need an Xbox Live Gold account to use Xbox Game Pass, though you will need it if you want to enjoy any of the online multiplayer features on offer.
Can I get Xbox Game Pass on PC?
While Xbox Game Pass, as the name suggests, has been an Xbox exclusive for years, that's now changed. In the run-up to E3 2019, the company revealed that Xbox Game Pass is headed to PC, with PC gamers able to enjoy the same subscription-based game experience as console players - although there are differences between the offerings, despite sharing the same name.
Microsoft has confirmed that there will be over PC 100 games to dip into by August, compared to a list of 200+ currently available via the Xbox One - though there are still plenty of major titles included, along with some PC exclusives like Imperator: Rome and Football Manager 19. Apart from that, you'll get the same launch-day-availability, discounts and other benefits available to Xbox One gamers.
Game Pass on PC is available in open beta right right, with no official launch date set yet - though Microsoft's promise of over 100 games by August suggests that might be when it launches officially.
How much does Xbox Game Pass cost?
The monthly subscription fee for either the Xbox One or PC version is £7.99/$9.99, which is substantially cheaper than the £12.99/$19.99 monthly rate for PlayStation Now, the service's closest rival. Note that this gets you one or the other of the console and PC versions, not both.
If you like the sound of both, the best value option is Xbox Game Pass Ultimate: for just £10.99/$14.99 per month you'll get Xbox Game Pass for both console and PC, and Xbox Live Gold thrown in too. Given that those would normally add up to £23/$30 all together, this is a pretty massive saving.
There's no option to rent individual games on either service, but there's a 20 percent discount if you decide to purchase any of the games while they're still part of the Game Pass catalogue, with a further 10 percent off any DLC or other related purchases - though that only applies to Xbox One titles, not the 360 games.
If you're tempted but don't yet own an Xbox, you may want to take a look at Microsoft's Xbox All Access subscription service, which is essentially Game Pass Ultimate but with a console thrown in too.
What games can I play?
Xbox Game Pass has over 100 games from the Xbox One and Xbox 360 on the service at any given time, but the lineup will change over time, with new titles added "every month".
Just about all of Microsoft's own games are included of course, with many major titles actually arriving on the service the same day they launch. Microsoft is working with major publishers including 2K, 505 Games, Bandai Namco, Capcom, Codemasters, Deep Silver, Focus Home Interactive, SEGA, SNK, THQ Nordic, and Warner Bros, so there should always be a decent variety of titles available.
To see a full list of titles on the service at any given time, head to the official Xbox Game Pass site and scroll down the page. You can also check out our round-up of the best Xbox One games to get an idea of which games to prioritise playing.
Click here for the best Microsoft voucher codes.