"Too many creative playgrounds are designed so they look nice esthetically just like a wooden deck in your backyard," says New York architect Bob Leathers. "But a playground has to go one step further. It has to be an all-involving environment with new activities to explore, each as exciting as the one before."

While traditional playgrounds may have a set of swings, a slide and a climbing apparatus, each separated from the other, Leathers attempts to design his play areas as integrated structures.

"I realized early on that children like a series in play structures," says Leathers, who claims hundreds of hours of watching children play.

"What this means is that play is a continuous experience in which children can be more spontaneous and creative."

As children move through the play sequences, each area is designed to test different skills at different age levels. For example, the cable bridge, including two hose railings and one hose to tightrope across, can be used in a variety of ways. Children at 5 or 6 years may walk across holding onto both railings. By 11 or 12, they may be able to walk across without holding onto the railings, and some children use the railings as parallel bars.

Within two weeks most children have found their way through the maze to the castle, but in different ways. While younger children may work their way through the decks, tunnels and bridges at random, older children can see the pattern intellectually.

"Children never totally master the playground until they are between 12 or 14 years," says Leathers. "There is always another challenge just beyond their capability, so it never becomes boring.

"A lot of creative playgrounds aren't as creative as they should be, because there is just one course. There should be at least three different directions a child can take from each point, if not four or five, so the play area becomes a huge labyrinth with hundreds of choices."

Leathers also is skeptical of playgrounds with log forts and spaceships which "adults think look great. But it is even better if you use more general shapes so that the children can use their imaginations.

"On one day the children may pretend they have to cross the suspension bridge over crocodile-filled waters to get to their 'safe house,' sometimes a castle. On another day the castle may be transformed into a spaceship."

The multilevel decks, slides, tire bridges and tunnels are arranged in what Leathers terms an "irrational design with its own logic."

"If you are designing a home, you have a rational series of corridors and rooms that are easy to understand. But in a playground you don't go from point A to point B. The only way to get from a platform three feet off the ground to a lower level may be to climb up to a 6-foot-high platform and then down a slide."

The point children usually aim for is the castle, which Leathers says is especially popular. "It provides an opportunity to be higher than everyone else. Children are looking up all of their lives, so they like to get to the top and look out. And, by watching the other children playing, they are also learning new skills."

The newest feature added to the playgrounds, by popular request, is a dungeon in the castle complete with painted monsters on the walls. The children submit their own pictures, and final selection is based on the scariest--but not too gory--monsters.

Designing playgrounds, says Leathers, is like play itself. "Both are an ongoing process that never really ends."