Oh, could be any sort, really. Haven't actually encountered anything like this before. I mean, I was trapped in a dream once by an alien. Twice...actually, could be something like that where we're all sharing a subconscious experience. But everything feels real, so I can't tell. Gotta think about that one now.
There are all sorts of possibilities in this universe- well, all of these universes. Lots to figure out.