Translating Elementary Cellular Automata into Tangible Gameplay: Design of Shellmate

This paper presents a case study of Shellmate, a two-player tabletop strategy game designed by translating the structural principles of Elementary Cellular Automata (ECA) into tangible gameplay. Its central claim is that a simple computational model can serve as a design foundation for non-digital games, and that such games can foster computational thinking behaviours such as pattern anticipation, forward planning, and adaptive reasoning without explicit instruction. The authors position this as a contribution beyond the largely instructional or digital-interface approaches that dominate existing computational thinking game research.

The design was developed through iterative prototyping across three versions, with each iteration addressing balance problems such as first-player advantage, overreliance on filler placement, and disproportionately powerful rule cards. A key finding is that strict adherence to a complete ECA simulation was incompatible with playability; deliberately leaving some neighbourhood combinations undefined within each round introduced uncertainty and player agency, which the authors identify as the mechanism that drives engagement and reasoning. The final scoring rewards the length and number of diagonal formations, and a capturing phase was added to heighten conflict.

Evidence comes from playtesting with 10 participants in pairs over two rounds each, with sessions of roughly 30 to 40 minutes followed by brief interviews. Participants showed progressive improvement in rule card selection, and blocking and diagonal anticipation emerged as dominant behaviours. The authors are explicit that this evidence is qualitative and drawn from a small sample without a structured evaluation instrument, which limits generalisability. Reported friction points included confusion over turn order after row completion and the cognitive load of reading diagonals during scoring, and the authors suggest that digital or hybrid versions could address these issues.