"The old playground installations were not designed for the use of just one child," he says. "They took group effort - like the carousel of wood and metal. Children must push together to get the heavy wheel spinning and jump on when it gathers speed. Children learned social skills in the process.

"Slides also used to be very tall and were made of wood or metal. Now everything is made of plastic. Climbing frames could be up to two storeys high. I enjoyed climbing all the way to the top as a child."

When he was growing up, safety features weren't a factor in playground design and if children fell, they just picked themselves up, Leung says.

He believes this helped nurture children's resilience: "They had to make judgments about whether to proceed up [a climbing frame] or think about how to overcome obstacles. But today's playgrounds are not challenging at all."

While no one suggests neglecting safety considerations, experts agree that the city's playgrounds have become dull and boring.

The oldest existing playgrounds, which were built in the '70s, were much more fun for children, but they are fast giving way to dumpy, homogenous plastic slides and swings.

Hong Kong has an estimated 1,000 public playgrounds under the supervision of the Leisure and Cultural Services Department; others located in the city's 137 public housing estates come under the remit of the Housing Department. But the government does not have guidelines on safety standards or criteria for playgrounds

"Hong Kong playgrounds are monotonous in their design," says Chris Yuen Hon-cheong, a US-certified playground safety inspector who also consults for the Hong Kong government on their design.

Overseas, there are different kinds of swings such as those with diaper-shaped seats for babies and others with a plate that carries the whole of a child's body and can swing in a circular motion. Other fun features include watery surfaces dotted with fake lotus leaves that children can jump on, as well as sand pits and areas with mist sprays so they get a different experience, Yuen says.

"A playground should enable children to develop their senses as well as develop physically and socially. Hong Kong's playgrounds only provide physical play."

Because there are no playground equipment suppliers in the city, the government turns to overseas companies that design facilities based on instructions from local officials. So if the set-up comes from the US, they adopt American standards, and European Union rules if the maker is from Europe.

Kathy Wong Kin-ho, president of the Playright Children's Play Association, attributes the cookie-cutter set-ups at local playgrounds to overprotective parents and bureaucrats keen to avoid complaints about children's injuries.

"They associate height with danger. That's why slides are getting shorter and shorter," Wong says. "Slides should offer at least three levels of difficulty that people can choose from.

"Like in the West, they promote the concept of inclusive playgrounds where anybody - young and old, parents and children, the able-bodied and disabled - can play.

"In Hong Kong, you see parents stand by and wait while their children play. Even children find the set-ups boring as they are too safe. Urban playgrounds are an important venue for children to get all-round development through play. But local playground design does not cater to their needs."

Among other things, many playgrounds in Hong Kong lack any element of nature in their set-up, says Susan Goltsman, co-founder of US design company MIG, who visited Hong Kong in 2013 for a study on inclusive playgrounds at Playright's invitation.

"Unlike those in Hong Kong, playgrounds should be made of more than rubber. There should be grass in some places, concrete, gravel, metal, wood, water, sand and every kind of material you can imagine in other places," Goltsman says.

"Play is not a clean activity. Children need to get dirty, be able to manipulate and build things. Playgrounds are not about safety and rules, but about providing the right activity for children."

For example, installing enclosed slides and netting can reduce the risks associated with heights, she says. "The design supports the activity, not the other way around."

Tuen Mun resident Ng Wing-yan agrees. Playgrounds in her neighbourhood are boring with standard plastic structures, says Ng, who has a six-year-old son.

"I miss the long metal slides that ran from the top of a small hill all the way to the ground, even though they could be quite scary. But these were all demolished because of safety concerns. Sometimes, I bring my son to Hong Kong Park to enjoy the greenery. He liked the yellow slide, which is now gone. You had to walk up a long flight of stairs to the top to slide down. It was one of the few remaining long slides that had height. But it was also safe as it was an enclosed. I don't know why the government had to remove it. Children need a bit of excitement when playing."

Several researchers have found that children actively seek some risk in play, and believe the curiosity and desire for excitement that drives such behaviour is how they "rehearse" and learn to cope with real life challenges.

Ellen Sandseter, a professor of psychology at Queen Maud University in Norway, has identified types of risk that often attract children at play: speed, heights, being near potentially dangerous elements such as water, dangerous tools such as knives, rough-and-tumble activities such as wrestling and wandering away from adult supervision.

Writing on the developmental benefits of risky play in the journal last year, Sandseter acknowledged that it is not an easy balancing act to give youngsters the chance to play freely in stimulating environments while ensuring they do not come to serious harm. But she believes safety concerns should not result in restricting children from engaging in challenging play activities. "Paradoxically, risk-avoidance puts children at greater risk because they may miss out on important developmental benefits. Through risky play, children prepare themselves to handle 'real risks and dangers'," she wrote.

To boost awareness of stimulating play environments, Playright has organised a playground design competition which attracted more than 50 submissions from professional and student groups in May. Contestants were asked to devise plans for a 3,000 square metre area in Tuen Mun Town Park, including a 350 square metre play zone for children.

Since the contest was jointly organised with the government, Playright is in talks with officials about the possibility of using the winning design to update the playground, which is due for a major overhaul, Wong says.

Planners should consider the park as a whole in their design, Wong says. Besides swings and slides in the play zone, the surrounding area is important, too.

"How planting and seating are done and how routes are laid out can affect the flow of play and how children interact with nature. For example, outside the play zone, you can place a tree with a hole at the bottom to serve as a hiding place. Tree stumps can also serve as stairs or steps for children to play amid nature."

Goltsman says: "Hong Kong has very restrictive playgrounds. In Denmark, Germany and all over Europe, you can find fabulous playgrounds with creative design.

"Children need climbing structures with height to learn about balance. Children have biological needs to develop many things through play. For example, swings provide vestibular motion to develop the inner ear. If you don't provide that to children, you need to bring them to places where they can twirl and get dizzy at a certain age.

"Safety doesn't mean boredom."