In a dense urban-village alley, children co-designed a modular playground that converts play into electricity—seesaw-powered Ferris wheel, bike spin disk, 360° gyro and comic-strip hamster wheel. Crowdfunded ¥80 000 and erected in 20 days, it logged 1 000+ sessions its first weekend, produced energy for 300 phone charges, survived a Category-17 typhoon and served as the community’s sole emergency charging hub. It shows how joy, resilience and green energy can weave into everyday neighbourhood life.