Programming interactive networking applications for mobile devices is currently a laborious process, due to the lack of standardized development support. We introduce a new software platform, OpenTrek, primarily intended to assist the development of multiplayer networked games on Pocket PC devices. OpenTrek is similar to game development environments on stationary PCs, such as DirectX, but is fully optimized to work with mobile devices. It is a freely downloadable package with a fast learning curve, which includes support for ad hoc networking and efficient graphics. We successfully deployed OpenTrek in a course at a local university. 28 students with no previous experience in Pocket PC programming were able to create 12 different advanced multiplayer networked games in only five weeks (which included introduction to the platform). By easing the development of advanced interactive applications on Pocket PC, OpenTrek can lower the hurdle for researchers who wish to prototype and test novel user interfaces for mobile devices.