"Steven was always a leader. He is able to combine creativity with technical skills and a good sense for business opportunities. These skills have led him to becoming a successful entrepreneur in the tech industry," Tomitsch says.

During that two weeks of the Vivid Sydney Light Festival, dozens of people stayed in lines each day to experience TetraBIN, especially children.

Bai says: "people walking by would smile to our Tetra-BIN. Bringing the cold public space a fun experience makes me feel accomplished because I can use my knowledge and ability to change the public space, which inspires me to move forward".

Bai says he would observe how people, especially children interact with the Tetra-BIN. "Each person has their own reaction, based on their understanding of the Tetra-BIN. There are no rules, no winning or losing for playing the Tetris, that's the magic of playing games," he says.

"We want to bring this experience to many places in the world, not only on the streets in Sydney," he says.

Smarter city

He thinks the infrastructure in the cities hasn't changed much during the past 30 years.

"I want to bring the apps and the technology into public spaces and trash cans can be a good entry point."

Bai and his team created a special version of the Tetra-BIN for recycling milk powder cans. "We also created software such as WeChat mini program to interact with our products such as TetraBIN," Bai says.

Bai takes TetraBIN as both a recycling bin and an educational product. "It can have multiple functions for example, we can show signs to the bathroom for visitors if it is placed in a museum or post notices for missing persons."

By far there are around 400 TetraBINs on service across the globe including US, UK, Japan and China.

Bai says he hopes Tetra-BIN can be a steppingstone for people to realize that public space can be fun.

"The city is an efficient platform for people to live and a modern city can be a carrier for happiness which provides a space for people to reduce pressure," Bai says. "I believe future cities will be a more open engine and carrier for experience and happiness, like a smartphone as a carrier for apps."

Bai thinks what his team are doing is to bring more experience and happiness to the modern cities. "We encourage people to take city as a party," he says.

"From the bench that plays a symphony to the recycling bin that plays Tetris, we want to combine innovation, technology and behavioral psychology to change people's way to interact with the public space or the city," he says.