I can’t point you to rules, but I can point you to news articles talking about the rule change from ~10 days ago:

https://www.macrumors.com/2024/04/05/app-store-guidelines-em...

Until now, emulators have been rejected under this rule

> 2.5.2 Apps should be self-contained in their bundles, and may not read or write data outside the designated container area, nor may they download, install, or execute code which introduces or changes features or functionality of the app, including other apps

I.e. "all the code this app ever runs has to be there when the app goes to app review"

This rule change on January 29 allowed for mini games and streaming games

> 4.7 Mini apps, mini games, streaming games, chatbots, and plug-ins: Apps may offer certain software that is not embedded in the binary, specifically mini apps and games, streaming games, chatbots, and plug-ins.

And then specifically this addition on April 10

> 4.7 [...] Additionally, retro game console emulator apps can offer to download games

is what allowed retro game emulators.

Source: https://www.appstorereviewguidelineshistory.com

Technically they were not forbidden, but it was impossible to play copyrighted ROMs.

The rules forbid running arbitrary/user-loaded code and copyright forbids bundling the ROMs people wanted to use.

The new rules have an exception for specifically emulators

Ask the author of this emulator whose app was rejected multiple times in the past six years

Which part of the App Store makes you think that the rules are ever applied as written?