Opera Philadelphia's whirlwind O17 festival looks to have accomplished the unprecedented: Five productions opened and played over the course of a week and a half — often right on top of each other — with three world premieres in the mix and not a dud to be seen. Might this be a landmark in Philadelphia's haphazard operatic history?

Singers, productions, and the audacious ideas behind them emerged with a solidity that defies the usual odds that only one in four operatic premieres turns out to be a keeper.

That was the consensus gleaned from critics (both local and national), box office figures (productions were either sold out or met Opera Philadelphia's projections), and, most interesting of all, intermission talk. Though some O17 premieres were a bit rough around the edges, the works themselves earned acclaim for having something important to say and having said it with clarity. Or with an intoxicating lack of clarity, as in the dream-like opera The Wake World.

The O18 festival is already in the works, Sept. 20 to 30 next year.

About 39 percent of the ticket buyers, according to preliminary figures, were first-timers. Some audience members I talked to came to O17 from the Broadway musical world. The hyper-visual, computer-animated production of The Magic Flute (imported from Berlin's Komische Oper) wasn't exactly the same experience as Wicked, but close enough for some. Those who frequent edgier, Off-Broadway-style theater attended some of the pieces that weren't in typical venues, such as the Philadelphia Museum of Art (War Stories) and the Barnes Foundation (Wake World).

There were also some returning opera devotees who had left the Opera Philadelphia fold decades ago for Metropolitan Opera subscriptions. They found the production values rather higher than the old days, when the spotlights couldn't always find the singers onstage.

And then there were those hearing opera for the first time — probably most of the audience at the Wilma Theater student matinee Wednesday for We Shall Not Be Moved, the opera that looks back at the MOVE bombing of 1985. "One minute I was on the verge of tears," said 17-year-old Melissa Fequiere, who was part of a Northeast High School contingent. "Next minute I was on the edge of my seat."

Others cheered the opera like a sports victory. And it is an opera. Though often described as a hybrid work, We Shall Not Be Moved has firm operatic roots, thinly disguised by modern urban rhythms. Fequiere and her friends even commented on the power of high notes.

Not everybody was likely to leave every performance happy. Strong-minded viewers mean strong opinions. What you did not hear were listeners dismissing the festival because the shows were, say, poorly done, as in the similarly configured but often-disastrous Vulcan Lyric festival of 2015. O17 was meant to increase Opera Philadelphia's footprint regionally and nationally, and about 36 percent of the ticket buyers, according to preliminary figures, came from out of town. So did some of the best reviews.

"I don't know if the tightly scheduled, multi-venue model of O17 can be imitated anywhere else, but Opera Philadelphia's spirit of adventure is certainly inspiring to the entire field," Opera News editor-in-chief  F. Paul Driscoll told me by email.

"This may be the way to go," critic Anthony Tommasini wrote in the New York Times.

O17's vocal roster had few star names. But up-and-comers such as soprano Cecelia Hall, mezzo-soprano Kirstin Chavez, tenor Ben Bliss, and baritone Jarrett Ott were as fine as I could hope for. So, critical disagreement was on a high level and on aesthetic grounds. You could dislike The Magic Flute and still be knocked out by the production's ingenuity.

Amid such discussions, Opera Philadelphia would seem to be taking its place in the city's intellectual community. (Yes, there is one.)

And the disagreements, specifically?

Elizabeth Cree, a Jack the Ripper opera that approaches its subject with autopsy-like objectivity, was considered "soulless" by the Wall Street Journal's Heidi Waleson, while Opera News' Driscoll liked  it "very much."

My Inquirer colleague Peter Dobrin enjoyed The Magic Flute's portrayal of the opera's villain, the Queen of the Night, as a computer-animated praying mantis. I felt particularly sorry for soprano Olga Pudova having the physicality of her portrayal being hijacked by such overwhelming images. Dobrin maintained his equanimity. Due to overstimulation, I left with a headache.

Composer David Hertzberg's music in The Wake World inspired some of the best critical writing of the festival. Waleson: "The sheen and muscle of Strauss wedded to the diaphanous spirit of Debussy." Tommasini: "The score, spiked with modernist elements, makes Mr. Hertzberg seem like a 21st-century Ravel." Dobrin: "A half-remembered dream Szymanowski once had about Scriabin."

Unique perspective came from Robert B. Driver, who visited O17 and ran a very different Opera Philadelphia between 1991 and 2011. He said the strides made by Opera Philadelphia since his departure were what you'd expect over 20 years, not six.

But O17's success is also a barometer on how Philadelphia has changed. Audiences once adored the star casts brought in during the 1970s with only a single rehearsal and also flocked to Driver's standard productions of standard repertoire. The current spirit of Opera Philadelphia is not to follow taste but to lead it.

That spirit is backed by Opera Philadelphia's in-house staff, one that shows every sign of working resourcefully with young composers in residence, workshopping what they do, and assembling the right team to do it.

The centerpiece of next year's O18 will be Lucia di Lammermoor, by A-plus-list director Laurent Pelly, which will be unveiled here and then go into the Vienna State Opera repertory. Such co-productions guarantee that Opera Philadelphia has a national and international footprint as they travel on to places such as New York's Apollo Theater, where We Shall Not Be Moved plays Oct. 6 and 7 before going on to the Hackney Empire, a historic East London venue that's remaking its name with edgy programming.

A certain amount of luck was with O17, since new operas can be derailed by subtle factors that nobody sees until opening night, especially when the piece is written in less than a year (as Wake World was). I used to be happy that new pieces such as Jennifer Higdon's Cold Mountain had a trial run elsewhere before coming to Philadelphia. Now, more than most opera companies, Opera Philadelphia is in a position to get most things right the first time. So, I'm relieved that Opera Philadelphia is originating next season's Lucia rather than inheriting something from Vienna.

Interestingly, the two O17 properties that came from elsewhere — The Magic Flute and War Stories — were what I call triumphs of packaging over substance compared with the rest of the festival.

It's crucial to say that Opera Philadelphia's festive new-opera mechanism wasn't created at the expense of core repertoire and the audiences who love it. There will be Carmen from April 27 to May 6, 2018. And I suspect I'll come to it with a fresher viewpoint than what is normally possible with this well-worn property.

The more my perspective is broadened, the more I appreciate the old masterpieces — especially knowing this isn't the only kind of opera I'll hear in Philadelphia this season.

O17 continues with performances through Monday. Information: 215-732-8400 or www.operaphila.org.