This study investigated whether an online serious game can be designed to engage and provide awareness of the 15-minute city. The 15-minute city has gained considerable policy and academic attention, but many citizens are unaware of this urban planning concept. The created game was a city builder where most essential services must be 15 min or closer to the residents’ homes. The game focused on transportation policies to promote walkability, cyclability, and public transport as an alternative to cars. 41 young European adults played the game and filled in a questionnaire, which included information about the 15-minute city concept and player engagement. Ten participants participated in an in-depth interview. Furthermore, three expert interviews were conducted with city planners who outlined city policies for the 15-minute city. The experts were interviewed before the game development and after the participant evaluation. The findings revealed that participants felt interested in the gaming experience and the concept of the 15-minute city. The online game was worthwhile playing, and most participants self-reported knowing more about the 15-min concept than before experiencing the game. Most participants answered and mentioned public transportation as essential in the 15-minute city, emphasizing bikeability and walkability. There remains a need for more focus on local context-specific elements and the incorporation of advanced technologies for the 15-minute city.