During conventional museum visits, some visitors are passive learners who only accept what is displayed in the museum. Especially in cultural heritage museums, it is important for the visitors to learn the significance of the legacy and form attachment to them to increase awareness of preserve them. We have developed a cultural heritage preservation serious game called “The Guardians” which is designed to be played on mobile devices. Serious game is a game designed with the intention of improving some specific aspect of learning or training. By playing “The Guardians”, players can actively learn about and form attachment to world heritage registered by the UNESCO. Game play of “The Guardians” consists of five distinct stages. First, a player can navigate in the game space and view brief information about both intangible assets and natural heritage. Second, the player can select a specific cultural heritage and actively learn about it then take quizzes about it. Third, the player can play contextual mini-games which protect or repair cultural properties that are in danger. This part shows why the heritage site is in danger and further shows ways to conserve them. Fourth, players around the world can communicate and form on-line communities. They can share their learning and cultural heritage saving experiences and cooperate to reserve them. Last, the game system allows players to donate to the actual cultural heritage that they have saved in the game. Usability test result for “The Guardians” was B+, which indicates that most players understood mechanics and intentions of the serious game. In interviews, the players said that “The Guardians” enabled active learning, increased involvement and engagement in cultural heritage learning experiences. Furthermore, players reported that increased attachment to the heritage was an important factor that lead to donation.