A Virtual World, the "Sustainability Hub" island, was developed and widely used during the COVID-19 pandemic, to support schools with distance-learning lessons, and the new mandatory Civic Education curriculum in Italy. Using a gamification approach, students learned about Agenda 2030 and sustainability focusing especially on themes related to geosciences, e.g., global warming, overexploitation of georesources and soil, recycling of critical elements, circular economy, and environmental footprint indicators. After a preliminary test involving 58 teachers, who evaluated the activity, 650 students from four schools in different geographic areas were involved. The students were divided into two groups, one directly accessing the virtual world as avatars (group W), the other participating in a sharing-screen mode (group S). Pre- and post-activity tests and a satisfaction survey were administered to assess learning outcomes and engagement. Questionnaire data analysis revealed good content acquisition for all students, high levels of students' engagement and positive feedback. The evaluation of post- and pre-activity mean score tests highlights significant differences between the two groups, with knowledge gain for the W group being double compared to the S group (22.9 vs. 11.6). This result evidences the positive effect of virtual world activities on learning. Sustainability Hub allowed interactions between students, supporting their social needs in a time of crisis, but it can also represent a valid support to conventional teaching. The engaging environment involved students to discover the many interdisciplinary connections between geoscience and sustainability, making them aware of the central role of geoscientists in the Agenda 2030 goals.