Fair enough. I haven't thought about it that way. Yeah, even Pokémon Go sometimes managed to get me to feel that a particular Pokémon is actually sitting there in the real world. It would probably happen much more often if not for the sorry state of GPS and orientation sensors in even top-tier smartphones.

That said, I think I get most of the "virtual/real reality mixing" feeling from the geographical aspect. In Ingress, I quickly started to feel as if the portals were a real, but invisible, part of my city. I'm starting to get something like it with Pokéstops. The important thing here seems to be persistence and non-randomness of that particular game world aspect.