This paper traces the migration of North American children’s television into the realm of massively multiplayer online games (MMOGs), and the issues this raises in terms of the commercialisation of children’s (digital) play. Through a content analysis of three television-themed MMOGs targeted to children, Nickelodeon’s Nicktropolis, Cartoon Network’s Big Fat Awesome House Party and Corus Entertainment’s GalaXseeds, I examine how this new development within children’s online culture operates in relation to existing industry practices of cross-media integration and promotion. Dominant trends identified in the content analysis are compared with emerging conventions within the MMOG genre, which is generally found to contain numerous opportunities for player creativity and collaboration. Within the cases examined, however, many of these opportunities have been omitted and ultimately replaced by promotional features. I conclude that all three case studies operate primarily as large-scale advergames, promoting transmedia intertextuality and third-party advertiser interests.