Digital, educational games have many promises (e.g., increasing students' content knowledge as well as competencies like problem-solving, spatial skills, and persistence). However, there are challenges to overcome before using these games more broadly in educational settings. One challenge involves identifying effective, theoretically based learning supports that do not reduce the fun/engagement inherent in gameplay. In our chapter, we focus on the design, development, and testing of various types of embedded learning supports (e.g., animations, worked examples, formulas, interactive definitions, and videos). We contextualize this discussion in terms of our ongoing research with the game "Physics Playground", currently being tested with middle- and high school students. We additionally elaborate on some of the challenges that we, as well as other educators and educational game designers, have faced in the design of optimal supports, concluding with ideas for future research. [This chapter was published in: Paloma Díaz, Andri Ioannou, Kaushal Kumar Bhagat, and J. Michael Spector (Eds.), "Learning in a Digital World" (p59-81). Singapore: Springer.]