Cheers erupted from the teams lining the sides of the field. The Files of Kicks had just scored an equalizing goal, propelling their team into contention for the final game. It was April 30, 4:30 p.m.

On the outskirts of Beijing, young Chinese entrepreneur Cheng Hao sits on an indoor soccer pitch – but this turf isn’t for humans. It’s where engineers working for his start-up, Booster Robotics, ...