PhilNote: video at link. Fun basic AR.
While in the AR Upside Down, the user can look around, viewing their world through a dark grey haze, from under the shade of a big, creepy tree. It's also possible to look back through the doorway into the real world, and once a person has finished exploring, they can step back through the way they've come - or, it they're feeling boring, they can simple take off their AR headset.
See the full story here: https://www.outerplaces.com/science/item/17454-stranger-things-augmented-reality