I think it is table tennis. Even though table tennis originated in England, it has been the most popular sport in China. Table tennis is one of the sports that have lowest threshold to play. Even if you know nothing about it, you can still play serval rounds with your rival, and sometimes just a wall can help you to practice your skill. It seems that every player can be quick learner and quickly find the enjoyment from playing it even without any professional equipment and venue. In Chinese people's mind, ping-pong is a whole body workout, and is also good for our eyes. As a ping-pong table doesn't need much space, most of the communities are equipment with ping-pong tables where to meet the residents' recreation needs.