Game-based learning environments hold significant promise for STEM education, yet they
are enormously complex. CRYSTAL ISLAND: UNCHARTED DISCOVERY, is a game-based learning environment
designed for upper elementary science education that has been under development
in our laboratory for the past four years. This article discusses curricular and
narrative interaction design requirements, presents the design of the CRYSTAL ISLAND learning
environment, and describes its evolution through a series of pilots and field tests. Additionally,
a classroom integration study was conducted to initiate a shift towards ecological
validity. Results indicated that CRYSTAL ISLAND produced significant learning gains on both
science content and problem-solving measures. Importantly, gains were consistent for gender
across studies. This finding is key in light of past studies that revealed disproportionate
participation by boys within game-based learning environments