This qualitative case study reports descriptive findings of digital game-based learning involving 15 Taiwanese middle school students' use of computational thinking skills elicited through programmed activities in a game design workshop. Situated learning theory is utilized as framework to evaluate novice game designers' individual advancement in developing a designer language, mindset, and use of computational thinking skills. Three strands of findings were extrapolated from analyzing observational data, participant-generated written responses and artifacts: Understanding games as systems and how components work together in meaningful relationships in game design; Developing growing sophistication in communicating with other novice game designers using language germane to game design; Improving understanding and application of computational thinking skills through game design activities. Extended discussions on three focal cases revealed that using design pedagogy, participants operationalized computational thinking skills in design tasks. Promises and pitfalls of using game design to facilitate computational thinking skills are discussed.