The 12th Annual Workshop on Network and Systems Support for Games (NetGames 2013) will be held in Denver, CO, USA at the University of Denver on December 9th-10th, 2013. NetGames brings together researchers and practitioners from academia and industry across the globe to present their latest research on the challenges of today's networked games, and to further understand the requirements and explore the possibilities of future generations of networked games. NetGames will also have an industry keynote and panel discussions with participants from both academia and industry. Submissions are solicited on all aspects of networked games, including (but not limited to): Scalability, cloud support, client-server, P2P, and mobile architectures Efficient message distribution and network protocol design Latency issues and lag compensation techniques Network traffic and game modeling and measurements System benchmarking, performance evaluation, and provisioning Operating system enhancements, service platforms, and middleware Massively Multiplayer Online Gaming (MMOG) Multiplayer usability and user behavior studies Personal communications and conferencing in games Mobile games, resource-constrained systems, and context-based adaptation Networks of sensors and actuators, networked haptics Quality of service, quality of experience, and content adaptation Dynamic and user-generated content authoring and management Content creation: non-linear storytelling, object capturing, algorithmic creation Security, authentication, accounting and digital rights management Cheat detection and prevention Social networking in multiplayer games