What if Robin Williams had never made it past a first audition? What if the now legendary performer had freaked out a jury of theatrical professionals with his quirky, spastic physical humor and never been given another chance?

That thought crossed Vicky Boone’s mind when she thought about starting a fringe theater festival in 1993.

As Boone sat with her collaborators Jason Phelps and Annie Suite in a long-gone Greek cafe on Congress Avenue, she pondered the arbitrariness of theater auditions.

“Sometimes the most interesting performers just don’t make it through a traditional juried process,” she says now. “What if someone is a really crazy genius and just doesn’t have the ability to conform?”

That really crazy someone could get a leg up at Frontera Fest, the performance event now celebrating its 20th anniversary.

The month-long festival — which to date has hosted some 2,000 performances — begins Tuesday at Hyde Park Theatre.

The majority of Frontera Fest consists of the Short Fringe — audition-less showcases featuring four to five performers each night who are given a maximum of 25 minutes on stage to do their thing, whatever that thing may be. Applications for a slot on the Short Fringe roster are taken on a first-come, first-served basis. Each year, between 90 and 100 performers apply for one of 80 Short Fringe slots.

At the time Boone, Phelps and Suite — then cohorts in the performance collective Frontera@Hyde Park Theatre — conceived of starting a theater festival, Austin was a considerably smaller city with a considerably smaller arts landscape. A festival might be a way to build community, the trio speculated.

“We wanted to have a festival that would be a level playing field and not be curated at all,” recalls Phelps.

“And we thought it would be a great way to meet everyone,” says Boone. “What if we just left the door open and let people come in and do their own thing.”

That open door morphed over the years into an invaluable incubator for Austin’s percolating theater scene, giving important early opportunities to some now nationally recognized artists.

In reading the credits in an Austin theater playbill these days, it would be a bit strange if you didn’t come across at least one reference to Frontera Fest in at least one bio of a cast or crew member.

Playwrights who have played Frontera and have national reputations include Pulitzer Prize finalist Lisa D’Amour, Kirk Lynn and John Walch. Steven Tomlinson, Ron Berry, Cyndi Williams and Zell Miller III are among those dramatists whose Frontera Fest pieces have gone on to become award-winning productions. And literally hundreds of Austin actors, dancers, designers or composers claim a Frontera Fest credit somewhere on their résumés.

Tomlinson — also a business consultant and professor — cut his teeth as a performer at Frontera Fest, trying out some of his early monologues. His play, “America Fiesta,” received the 2006 American Theater Critics Association’s Osborn Award for best new play and went on to have a successful off-Broadway run.

“Frontera Fest is the audience you want,” he says. “It’s supportive, playful and forgiving. It’s people who value process over product, who want to see something intimate, raw, emergent.”

As a member of the internationally recognized collective Rude Mechs, playwright Lynn also tried out some of his earliest work years ago on the Frontera stage.

“Frontera is a madhouse,” Lynn says in an email. Lynn’s play, “The Method Gun,” is on a national tour and the production has played in Australia and at New York’s Live Arts Festival.

“I think any chance for a creator of live performance to see his or her work in a live context is essential,” he says. “You can’t edit your work on the page. It’s a time-based live experience that has to be performed in that medium. It would be like a musician arranging all his music on a tin whistle. Writers need to hear the full range of the live moment including the audiences laughter and/or bored rustling.”

To celebrate Frontera’s 20th anniversary this year, Tomlinson and other a few other noted alumni will present new short works. (See box for more information.)

As for Boone, Phelps and Suite, they’ve all moved on. (In 2001, Ken Webster became artistic director of the organization, which changed its name to Hyde Park Theatre. In 2002 Hyde Park began collaborating with ScriptWorks, a playwrights’ service organization, to produce the festival.)

Now a successful casting agent for television and film productions, Boone says she sometimes has young 20-something actors come in for an reading or audition and excitedly tell her about their experience.

“They’ll ask me if I’ve heard of this great theater festival called Frontera that they’ve been in,” Boone chuckles. “I just smile and tell them I have.”