An essential way to lifelong learning in the modern information society is using ICT, geoinformation, and the concept of the so-called serious games, as well as gamification mechanisms. The „Smart City Alter Eco” game is a solution that not only facilitates social education for sustainable development but is also part of creating a so-called digital twin of a smart city. The authors propose an approach that enables creating a virtual model of a city, which reflects spatial, economic, social, and legal relations, as well as testing various versions of the city’s development. The objective of the game is not as much creating an operative biogas plant but making it an attractive solution to the environmental, economic, and social problems of the town of Żuromin in central Poland.