It could have been a website. I think some let you play emulated games in a browser window.

You can just download one from the App Store as of a year or so ago.

A lot of emulators are just apps, but the iso itself is a bigger mystery. My guess is an older sibling or even parent helped set that up. Nobody in their right mind would bundle a licensed game with an emulator on the app store.

I don’t think it was even an emulator, it was probably the official Nintendo port called ‘Super Mario Run’.

I would assume she has a nerdy family member or friend that assisted.