This study explores the application of the construct of guided play to the design of playground games intended to support inquiry-based gameplay and science content learning, while at the same time supporting students' positive affect—two outcomes that we do not often see improve together. We designed the games for middle school-age students to learn standards-based physical science concepts through play. We report on the design principles for guided play games and how these are instantiated in the case of two of our game designs. Furthermore, we report on a research study designed to determine the extent to which these two guided play games were able to promote affect, as well as support inquiry-based gameplay that resulted in standards-based science content learning. Our results suggest that our guided play games were able to produce these outcomes concomitantly.