Time: today. Setting: your place.

The air is filled with uncertain expectancy as purple-haired twentysomethings, urbane fiftysomethings and those in between stream into the loft.

The 40 or so people exchange smiles without quite mingling. Some head for the pingpong table, while others put on lipstick or pull beers from the fridge. One man tries to gauge the loft’s occupants by decoding the Post-collegiate Minimalist decor: an entry-level sofa with a beanbag chair, utility shelves supporting books that range from Grisham to Nietzsche.

The atmosphere is something between the first hour of a party and a real-estate open house, and it is, in fact, a bit of both. It’s the set on this recent evening of a form-meets-function theatrical production called “The Sublet Experiment.”

The play, a modern comedy of romance and real estate, has been performed since November in a roving series of apartments and lofts, garnering something of a reputation as a novelty even in a city full of theatrical innovation. As the New York Times put it, the play offers “the most titillating peep show in New York: other people’s apartments.”

Ranging from sprawling lofts to small one-bedrooms -- all but one occupied and offered free -- the play has appeared in three of the city’s five boroughs and across the Hudson River in Hoboken, N.J. The set consists of whatever there is in the host’s apartment, except for a few imported props. The audience has ranged from 12 to 40 people.

The audience sits around the space, and the action unfolds with an almost unnerving immediacy and intimacy. While spectators are politely reminded that they are just that -- not participants -- the setup doesn’t let the audience fade into the comfortable distance and darkness of a conventional theater.

“You always hope, when you’re writing a play, to draw the audience into the world you create. And in some ways, this is cheating,” playwright Ethan Youngerman, 29, who has had two other full-length plays performed in New York, says of his “The Sublet Experiment.”

But if the setup makes spectators feel like voyeurs -- and it’s hard not to while listening to intimacies in a stranger’s living room -- it is not without artistic purpose. Financial considerations initially inspired the idea of producing “The Sublet Experiment” in apartments, but Youngerman and director Michelle Tattenbaum quickly saw producing the play in people’s homes as a reflection of its themes of living in borrowed spaces. It is a cunning and swift-footed comedy that begins with an offer to share an apartment in exchange for sexual favors and goes on to explore the assumptions people draw about others from their surroundings.

“That issue of place having some impact on someone’s sense of identity seemed like a really great parallel to doing a play in different apartments,” said Tattenbaum, 30, who has directed several new plays in New York and summer-stock musicals elsewhere. She and Youngerman met as undergraduates at Yale University in the 1990s.

Tattenbaum’s and Youngerman’s friends and others have volunteered 13 apartments so far, enough to keep the show going at least through the end of April. The show, performed four nights a week at $25 a ticket, has yet to advertise. Its audience has been drawn so far from word of mouth, e-mail lists and news coverage, Tattenbaum said.

Hosts get free tickets, and the production staff supplies chairs for the audience, refreshments, clean-up, even toilet paper.

The producers advise hosts to clear their living rooms of valuables that might be easily filched, but nothing has been stolen or damaged to date, Tattenbaum said. The production nonetheless carries $1 million in insurance for injuries and property damage.