The New York Hall of Science, in collaboration with the Tufts Center for Engineering Education, the Learning Games Network, and New York City departments of education and of parks and recreation, is creating and testing two innovative science games to support student learning about frictional force and linear motion. SciGames integrates rigorous, highly motivating, data collection activities conducted in museum and playground settings, with in-depth data analysis and additional scientific investigation in the classroom. The primary goals of the SciGames project are to increase student motivation and interest in science and improve student learning about core physical science concepts. This exploratory project targets underrepresented urban students and their teachers from 20 schools in New York City (NYC) and through its partnership with NYC department of parks and recreation has great potential for scale-up throughout NYC, as well as dissemination to other urban communities. The SciGames model creates experiences for students that build on the positive, fun, free-choice learning characteristics of informal settings; promotes learning through repeated game-like experimentation and play; and supports students' sustained interest and learning in science classrooms where core concepts are formalized. The project is based on four design principles: (1) SciGames turns students' informal experiences into a game, (2) SciGames makes science content an integral part of game play, (3) SciGames generates data for further analysis during game play, and (4) SciGames, through the use of digital apps, supports students inquiring into data back in their classrooms. Researchers are developing the games using rigorous, well constructed, iterative cycles of design, development, testing, evaluation, and revision with different groups of NYC students and teachers. Pre and post data on students\' science learning and affect are being used to inform the design cycles. Over a two-year period, SciGames will produce two science games and associated digital apps, and a portable kit that supports game implementation, data collection and analysis. SciGames is an important experiment, combining the informal, engaging aspects of play with more formal science investigation to encourage and sustain the interest, participation, and learning of underrepresented students in STEM. This project has the potential to transform how we think of and structure science learning for middle school students.