Crossmedia games are a genre of pervasive gaming where a single game instance can be played with a variety of heterogeneous devices that support different forms of players' participation and deliver different game experiences. In this article we present the PM2G initiative, a service-oriented architecture aiming to support crossmedia game development and execution. Due to their relevance in this document, content adaptation and interaction adaptation services are discussed in detail. We also present, as a case study, a game called Pervasive Wizards, which is used to validate our architecture. Finally, we present some performance results obtained in our experiments.