The starting point is nowadays world, the general direction is that of a fantasy world, set in the past. Why the past? Because it's still present. Why fantasy? Because we were children and things didn't need to make sense, they just were and we had the flexibility to integrate them.
The characters are out there. One of them has forgotten her device. Another has broken it, the last one has no reception. They are isolated, they are not tunnelling their vision into the palm of their hands.
It's not a bad starting point, the characters have seen the same movies and read the same books as their players. They encounter a dwarf and start asking him: "Are you a Tolkien dwarf or more like a D&D dwarf?" The dwarf seems to acquiesce to the first one and the characters are embarked on an adventure where they think the Middle-Earth surrounds them.
At that point it might be good to roll or assign STR, CON, and DEX for each character and introduce a few rules. Give each player a blank sheet and let the rules flow as needed.
The gap between where the characters and they think they are should not grow too wide, the misunderstandings should zip from one side of it to the other, and play on their fantasy culture, standing as shaky reference points.
"This sword looks very simple but well made, but you have a feeling it is special, maybe it's simply that you are not used to, let's say, bespoke objects, and this definitely isn't the product of a set of industrial processes" — "Is it +1 or +2 ?" — "How would you know?" — "I'd set up a test bench..."
Magic could nest within the misunderstanding meanders and jump out of them.
Freies Kriegsspiel probably.