Gaming simulation is considered a “miniature garden” of a complex society. Most gaming simulation researchers have yet to learn how to gather thousands of participants. As a member of the UNESCO Creative Cities Network, Asahikawa City in Hokkaido, Japan, hosted a whole-city learning event called the Machinaka Campus (MCAN, “City Center Campus” in English) in 2022 and 2023. The event is aimed at providing an opportunity to present inquiry-based learning to Japanese students. The authors invited students who wanted to demonstrate their works, and 36 exhibitions were subsequently organized. The authors printed and delivered 27,000 leaflets to all pupils in the city and hosted a stamp rally with the exhibitors on a pedestrian-only road in the city center. In total, 63,000 people participated in the learning event. Some derivative movements emerged from MCAN beyond the authors’ control. MCAN may be a rare example of extraordinarily large-scale gaming that had once been considered impossible.