It's hard to believe the Pittsburgh New Works Festival is 15 years old. But the banter of Ricky Walters and Lynn Marie Woshner, who always take the New Works stage before and between plays to remind us to buy 50-50 tickets and turn off our cell phones, really drives the point home. Woshner convinces the audience that she was a mere babe in arms when the festival began.

This mature festival starts out with a very young play, Neil McGowan's "Flexible Flyer," produced by The Summer Company and directed by Jim Hee. In it, a couple deal with the disappointments and challenges of facing life and responsibility after their carefree teenage years. Dan (Christopher Bigos) reclaims his fire by pedaling cross-country on a tricycle. Nelly (Brandi Welle) seeks stability in a company job.

McGowan's notes reveal that he based the play on a man who set off to ride a recumbent tricycle cross-country, somewhat more believable than the tiny kid's tricycle that Bigos carries on stage. More than this visual stumbling block, the characters test the audience's credulity. They're sarcastic and mean before any relationship between them is revealed and, in a mere 15 minutes, they go from antipathy to love to resignation to bliss.

Welle and Bigos don't show a lot of depth in their performances, but there's really not much for them to work with. McGowan has his characters express every thought and emotion out loud, but the thoughts aren't very original or interesting and the result is a very one-dimensional production.

Laura Lewis-Barr's "Addicted to Mars" is a more sophisticated play. Produced by CCAC South and directed by Laura A. McCarthy, "Addicted to Mars" is a funny look at two people who shouldn't be together but can't seem to say goodbye. Although the title seems to indicate that the play is presented from the woman's point of view, both characters are intriguing and carefully drawn.

Lewis-Barr's writing drives the production, but it also shines thanks to McCarthy's tight direction and smart casting. Sara Gaille and Randy Allen Oliva perform with the ease of a longtime comic duo.

Gaille brings an entertaining quirkiness to Karen. She doesn't overplay Karen's insecurities, but she doesn't deny them either and the character is, therefore, very rich and wholly sympathetic.

Oliva is more broad in his portrayal of Nick, and it's the perfect choice for the role. Somehow Oliva makes Nick both overbearing and extremely likeable. His comic timing is superb and, even on CAPA's modified thrust stage, Oliva presents the entire audience with the full force of his very expressive face.

It seems that male/female relationships are the theme -- unintentional, most likely, as New Works doesn't traditionally group plays thematically -- as the third and final play of week one, Kim Zelonis' "Indiscriminate Avocados" also tackles the subject but with four people instead of two.

Old friends Matt (Scott Van de Mark) and Kate (Erica Highberg) try to sort out their relationship, while Matt's roommate Josh (Vincent E. Ventura) and girlfriend Trish (Diana Ifft) throw in their own issues and obstacles.

We don't learn a lot about these people in the play's 30 minutes, but Zelonis' writing is witty and honest. The characters feel real even if they're not the most creatively drawn. What would take them to the next level is for Zelonis to find out what makes them unique, not just types.

"Indiscriminate Avocados" (it would take too long to explain the rather unwieldy title) is smoothly directed by Adam Kukic. Its 30 minutes move quickly, and Kukic keeps it light and lively.

Mark and Highberg make a nice pair, and they play off each other well. Ventura is funny as the somewhat inept roommate, looking for love in all the wrong places. Ifft brings maturity to Trish, but she seems a bit out of place among these somewhat lost, somewhat stuck in their adolescence almost 30-somethings.

Produced by Unseam'd Shakespeare Company, "Avocados" is pleasant enough, not revelatory, but a nice conclusion to a set of mostly humorous "relationship plays."

The festival continues for the next three weeks. Shows are at the Pittsburgh High School for the Creative and Performing Arts, Ninth and Fort Duquesne Boulevard, Downtown, 8 p.m. Thursdays-Fridays; 5 and 8 p.m. Saturdays; 4 and 7 p.m. Sundays. 412-881-6888 or www.pittsburghnewworks.org. Cost is $25 for a festival pass; $10 for single tickets, with student discounts.