The grounds of Santa Rosa High School were taken over Saturday by kids in jet packs, grass skirts, togas, sparkly gowns, painted faces, swirling robes and all manner of kooky headwear.

A walk through the campus was a bit like being backstage at the theater — various cardboard structures, hanging backdrops, makeshift buildings and creatures stashed here and there amid weird assortments of props.

A gathering of Omers is like that: a little odd, always noisy, extremely colorful and heavily reliant upon duct tape, hot glue, PVC pipe, bedding and papier mach?

But the underlying enthusiasm and energy of the crowd is palpable. These are excited kids.

Odyssey of the Mind — OM for the initiated — is a creative problem-solving competition. Speed and physical strength are displaced by smarts and ingenuity that participants apply to problems contrived to provoke invention and teamwork while integrating knowledge and performance into one.

Saturday marked the annual Redwood Region tournament, the first step for top teams seeking to reach the state and then world competitions.

"It's a chance to be creative," said Veronica Morris, 7, a second-grader at the Santa Rosa Charter School for the Arts, "and it's really inspirational. It just shows you that you can do a lot of things if you try."

The international Odyssey organization issues a selection of official problems each year in various categories. They focus, for instance, on designing a mechanical contraption required to perform certain functions, building tiny balsa wood structures supporting hundreds of pounds, or highlighting examples of classic literature or art - all in the course of a skit with certain required elements and without parents' input or significant expense. There are time limits, too.

One problem this year required teams to build a vehicle to transport parts from one location to another for assembly into some kind of pet animal that could then perform a trick.

In another, characters had to represent parts in an email system that could deliver messages with different attributes through a central server and a spam filter.

In yet another, students were to create a musical performance that featured an architectural structure built between 1000 and 1600 A.D. with a plot in which three artworks disappeared, characters went on a quest, and the art then reappeared. With two songs and choreographed movement.

A team of Hidden Valley Elementary School sixth-grader was inspired by Moscow's colorful, onion-domed St. Basil's Cathedral and found themselves building a skit around pointy-capped gnomes in an herb garden.

"It's just really fun to figure out the problems and perform here," said Nathan Alexander, 10, a fifth-grader at Fort Bragg's Dana Gray Elementary School, who served as a knight in a play featuring ghost princesses at the "haunted" Conway Castle in Wales.

He said one of his favorite parts is assembling costumes from bits of odds and ends, using things such things as aluminum foil and spray paint to finish his sword and cardboard armor.

Sixty-five teams, or about 400 students, from Marin to Mendocino counties took part Saturday, divided by age division and selected task.

Among them was a group of Maria Carrillo High School students who managed to make a completely recognizable Flintstone-mobile mostly out of cardboard and plastic.

Their competitors, a team of Rincon Valley Middle School eighth-graders with a token Carrillo student who put them in the high school division, cleverly mimicked a roller coaster with a blocky cardboard cart careening and climbing in front of a vertical loop of paper sheeting drawn with a "track" that reeled continuously around a rod in a highly successful visual trick.

As the skit unfolded, two team members stacked round weights onto a 15-gram (about half an ounce) balsa wood structure that finally collapsed after reaching a whopping 551 pounds.

Most of the team members have been together for five years and stay involved just because they have so much fun together. They also remember an early competition in which Willits High School students watched them struggle and then came over and offered a variety of useful tips that have helped them since.

Anika Dhar, the only girl in the group and a Carrillo sophomore, said the team is reaching the point where, now, they can share, too.