Earlier this week, Microsoft finally announced that cloud gaming, based on the Project xCloud technology, will be launching as part of Xbox Game Pass Ultimate on September 15, but seemingly only for users on Android. Shortly after the announcement, it was discovered that the preview program on iOS devices was shutting down earlier than expected, and Microsoft hadn't mentioned iOS support anywhere.
Now, in a statement to Business Insider, Apple confirmed that it doesn't allow services like Game Pass on the App Store, and that's because games need to be submitted and reviewed by Apple individually:
"Our customers enjoy great apps and games from millions of developers, and gaming services can absolutely launch on the App Store as long as they follow the same set of guidelines applicable to all developers, including submitting games individually for review, and appearing in charts and search."
This raises a few questions. For starters, this condition applies to games, but seemingly not to TV shows or movies streamed from services like Netflix or Hulu. At the same time, services like Steam Link and Rainway also work, and the games on those services are also not approved individually by Apple.
The main difference there is that the games are hosted on your PC, rather than a cloud server somewhere, but that isn't mentioned in Apple's statement. Microsoft's service isn't the only one having trouble, as both Stadia and GeForce Now aren't available on the App Store. Again, these are all services that stream games from the cloud rather than a machine you own. A member of the Rainway team recently stated on Twitter that streaming from the cloud is actually what's causing the block, because streaming software is treated as remote desktop software, thus you can only connect to devices you own. Presumably, if you're connecting to the cloud, Apple interprets it as though you're using the platform to distribute games, and thus they need to be approved individually, but again, that wasn't mentioned specifically in Apple's statement.
In response to Apple's comments, Microsoft has also shared its own stance (via Windows Central) on the matter, lashing out at Apple for blocking cloud gaming services and treating gaming services differently from other apps:
"Apple stands alone as the only general purpose platform to deny consumers from cloud gaming and game subscription services like Xbox Game Pass. And it consistently treats gaming apps differently, applying more lenient rules to non-gaming apps even when they include interactive content."
Microsoft defends that games on Xbox Game Pass get regulatory approval from independent agencies such as the ESRB or PEGI, so there's no reason why they should be blocked.
While Microsoft says it doesn't have a path to brings cloud gaming to the Xbox Game Pass app on the App Store, it did say it's working on bringing the experience to iOS. Coincidentally, Apple's full statement had said that "developers can choose to reach all iPhone and iPad users over the web through Safari and other browsers on the App Store", so Microsoft's response seems to suggest that a browser-based experience could be in the works. Google's Stadia service is actually accessible on the web, but you need to use Chrome or a Chromium-based browser on a PC.