Apple tells emulator developers it's OK with retro games – not entire OSes

Updated A pair of developers have come away from encounters with Apple's latest rules regarding video game emulators in its App Store and concluded the iGiant is not okay with software that emulates a whole operating system.

The developers of DOS emulator iDOS and multi-OS emulator UTM both posted about Apple rejecting their wares from the App Store, which they submitted in the wake of iOS App Review Guideline changes made to comply with the European Union's Digital Markets Act (DMA).

The rule in question – section 4.7 – was added to Apple's App Review Guidelines earlier this year and allows for some software, like video game emulators, to access and download content outside their designated container area. The latest review effectively acts as an exception to section 2.5.2, which requires all apps to be self-contained and doesn't allow them to read or write data that introduces changes in functionality.

Chaoji Li, the developer of iDOS, said he was forced to re-submit his work for review of its suitability for the App Store after section 4.7 was added. Unfortunately, Apple doesn't think a rule designed for game emulators applies to his app.

"[Apple has] decided that iDOS is not a retro game console, so the new rule is not applicable," Li wrote in an update to an earlier blog post last week. "They suggested I make changes and resubmit for review, but when I asked what changes I should make to be compliant, they had no idea, nor when I asked what a retro game console is."

UTM's developers reported a similar experience: they submitted a version of UTM that doesn't use "just in time" compiling to run on iOS without needing a device to be jailbroken, and did so when section 4.7 was added to the Review Guidelines. Apple’s reasons for rejecting the app were the same as those applied to iDOS.

"[Apple's] reasoning is that rule 4.7 … does NOT apply to UTM SE" because "'PC is not a console'," the developer wrote in a post on X. "We will adhere by Apple's content and policy decision because we believe UTM SE is a subpar experience and isn't worth fighting for."

• Europe accuses Apple of preventing devs from telling users about world outside
• Apple Intelligence won't be available in Europe because Tim's terrified of watchdogs
• How Europe can force Apple to support competition
• European Commission may be about to put the squeeze on Apple for its App Store rules

UTM SE was also rejected from certification for third-party app stores in the EU, the developer said, based on section 2.5.2 because section 4.7 only applies to apps published in Apple's App Store.

Regardless, it seems possible Apple isn't being entirely consistent with its reasoning for the OS emulator ban. The rules concern apps being allowed to go outside their binary to fetch content that can alter their functionality – something both console games and OS applications are able to do.

Of course, there's an easy security argument to be made for why Apple doesn't want to allow users to emulate entire OSes on their iPhones. The iGiant has long opposed sideloaded apps and warned users not to use them on the grounds that any code Cupertino can't vet could carry security and privacy risks. An operating system is far more complex than a single app, and could introduce many more security issues.

We asked Apple to explain its rejection of the OS emulators and will update when/if we hear back.

Apple was also accused this week of violating the DMA by EU officials on grounds it hasn't complied with rules permitting app developers to steer users outside the App Store for purchases. ®

Updated to add on June 26, 2024:

UTM's developers told us that UTM SE was the only app they submitted. "Regular UTM requires entitlements that Apple does not provide to 3rd party iOS developers for JIT and so there is no way to submit it."

They added: "UTM SE will continue to be distributed in unsigned form for jailbreak users and owners of enterprise signing certificates and developer signing certificates."