This design case describes the development of three analog games intended to introduce middle school-age girls to core computer science (CS) concepts. We describe the learning objectives, game mechanics, and narrative elements of each game, and some key problems and decisions that we confronted during the design process. Our design process was guided by two key goals and assumptions: (a) the games should help players develop a "situated" understanding of CS concepts through engaging them in computational thinking (CT) practices associated with each concept, and (b) game mechanics and story elements should be meaningfully integrated with and supportive of the games' learning objectives. We discuss several challenges that we encountered in the design process, both in identifying CT practices that lent themselves to game mechanics, and in finding ways to embed mechanics into stories in a meaningful way. Data from gameplay sessions suggests that, on the whole, girls found the games engaging and improved their understanding of CS concepts. However, we conclude that we were only partially successful in achieving our design goals. Testing the facilitator guides with a broader set of users and integrating the facilitator role into gameplay and story are potential goals for future work.