In the last two decades, game-based learning environments have evolved into powerful learning tools. With the growth and evolution in complexity of these innovations, complementary work in game-based assessment design has also begun to take shape and has generated considerable interest among a variety of education stakeholders. This is in part due to their ability to offer real-time, adaptive and integrated formative feedback. As the use of digital devices and digital learning tools continues to expand in schools, the potential for harnessing learning data becomes increasingly possible and powerful. Yet there are inherent tensions and challenges in the nature of collecting assessment data inside a game-based learning environment which confront our foundational premises of what makes for a good assessment. In this article, we explore the evolution and opportunities of the emerging field of game-based assessment, the challenges and tensions these innovations present and how we may be able to collectively advance this work to benefit everyday classrooms.