An old-ish idea. Was reminded of it walking through a mostly empty park on the way back from a midnight screening of the Dark Knight Rises.
It came about while I was in an introduction to theatre class. We were putting on 15-minute plays that students in the class had wrote, and I found that I kind of liked doing the read-throughs of the script. The basic idea was (is) theatre without an audience. Theatre solely for the benefit of those involved. Now, having people watch who aren't involved in the actual play wouldn't be FORBIDDEN, exactly, but it wouldn't be the main point.
(And yes, I know an audience is technically a fundamental part of a stage production, but if it helps just think of the actors doing double duty as characters and spectators. M'kay?)
The original idea was a group that would meet to do readings of plays (and occasionally minimal productions), both closet drama and not, in private (with a focus on material written by members, I think, but that part isn't as important to the basic concept). Also, not much pressure would be put on members to memorize material. If you need to have the script in front of you? No big deal. Forget a line? Also not a big deal. We're not performing for other people, so in my mind those things aren't as important. Plus this would allow for spontaneity. If someone/everyone is in the mood to do a particular play, they can just do it right then and there as long as they have the script or can easily print it out or whatever, and read straight from that. But considering that a closet drama is already a thing, this idea doesn't feel too innovative as I re-visit it.
Now we get to the part that the empty park plays in this. The new part.
The short version is that the group would also do performances in quiet, deserted places. Like a park late at night, or virtually any place at night, or places that simply don't see that many visitors for one reason or another. Places where they likely won't be seen unless the see-ers actively seek them out, or are invited. The productions would probably be minimal (wearing your own clothes, cardboard swords, etc.), and what I picture is sort of a half play, half LARP.
The pretentious-poetry version is that the group would pull pieces of things that never were into spaces that hover at the edge of a society's awareness.