The innovative Erasmus+ project EXCALIBUR (Expanding Content and Language Integrated Learning through Building a Sustainable Future in Realtime, 2022–2025) enabled upper secondary learners from six European countries to collaboratively explore issues of sustainability and develop solutions for safeguarding our planet. The participants used virtual 3D game-world environments as online collaboration platforms—tools typically associated with informal leisure contexts—which facilitated the transfer of informal learning elements such as immersion, flow, and affinity spaces into formal educational settings. In parallel, they developed their intercultural communication and language skills in English, German, and other foreign languages functioning as lingua francas within a Content and Language Integrated Learning (CLIL / CLIL LOTE; Languages Other Than English) framework. While CLIL (LOTE) is usually implemented only in selected schools, the EXCALIBUR project demonstrated how it can also be successfully adopted in mainstream educational settings.

Qualitative data and method triangulation was used. The modes of observation varied and ranged from simple non participant observation to participant observation using one’s own avatar in the game, and even to acting as a participating game mediator. During selected phases of the gameplay, multimedia documentation was created, i.e., recordings of actions taking place in the 3D game world. At the same time, the game’s chat function enabled the documentation of written communication between participants. In addition, the researchers involved took notes on their observations, feedback questionnaires were also used. The research material was analyzed qualitatively; among other methods, thematic and content analysis were applied.

Several game-based approaches were developed during the project using the sandbox game Minecraft and the game engine Minetest (now Luanti): a) Plain World Setting, where learners freely apply their creativity to construction tasks based on prior topic-related research; b) Scenario-Based Worlds, where dynamic changes in the 3D environment necessitate player (re)actions, with a focus on target-language use, plurilingual interaction, and project skills such as web-based communication and information searching; c) SERASUM: For a Better Tomorrow, a global simulation in which young participants from different countries were trained as “agents of sustainability.” The results from the EXCALIBUR project are interesting among others from the perspective of multimodal, authentic, action‑based learning environments. The created online project approaches showed to be genuinely learner‑centered and enabled international, creative collaboration without the high travel costs typically associated with exchange activities. Notably, enthusiastic leisure-time computer gamers—who are not always the most motivated students in formal school contexts—became highly engaged and often assumed responsible roles within the collaborative game teams. The project even received the European Language Label Certificate. Regarding intercultural communication, the need for prior training proved to be extremely important.

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