This study investigates how pre-service teachers engage with spatial scale reasoning through epistemic games - structured approaches to scientific inquiry and problem-solving. Three primary school pre-service teachers in their third year participated in an activity requiring them to arrange and explain the relative sizes of objects ranging from subatomic particles to astronomical bodies. Through qualitative analysis, we identified three major themes of epistemic games: Cognitive anchoring (using objects, numbers, or experiences as reference points), Object relatedness (understanding relationships through analogy, nestedness, and interaction), and Perspectives (considering contextual and representational viewpoints). While the pre-service teachers employed similar epistemic games as science experts from our previous research, they demonstrated unique engagement through their pedagogical expertise, particularly in considering contextual perspectives. However, the pre-service teachers made more errors than experts, especially when dealing with microscopic objects, despite using similar reasoning strategies. This suggests that the effectiveness of epistemic games depends on underlying conceptual knowledge. The findings have implications for how we prepare teachers to support spatial thinking development in students and highlight the importance of both strategic reasoning and accurate conceptual frameworks in spatial scale understanding.