Massively multiplayer online games (MMOG) is an innovative and challenging class of applications for Grid computing that require large amounts of computational resources for providing a responsive and scalable gameplay for concurrently participating players connected via Internet. We present our Real-Time Framework (RTF) – a Gridbased middleware for scaling game sessions through a variety of parallelization and distribution techniques. RTF is described within a novel multi-layer service-oriented architecture that comprises three advanced services – monitoring, capacity planning, and runtime steering – that use the potential of Grid computing to provide pervasive access to a potentially unbounded number of resources. We report experimental results about the quality of our capacity planning and scalability of the RTF distribution mechanism.