Despite significant advancement in ontology learning, building ontologies remains a task that highly depends on human intelligence, both as a source of domain expertise and for producing a consensual conceptualization. This means that individuals need to contribute time, and sometimes other resources, to an ontology project. Now, we can observe a sharp contrast in user interest in two branches of Web activity: While the “Web 2.0” movement lives from an unprecedented amount of contributions from Web users, we witness a substantial lack of user involvement in ontology projects for the Semantic Web. We assume that one cause of the latter is a lack of proper incentive structures of ontology projects, i.e., settings in which the perceived benefits outweigh the efforts for people to contribute. As a novel solution, we (1) propose to masquerade collaborative ontology engineering behind on-line, multi-player game scenarios, in order to create proper incentives for humans to help building o...