Starting from the difficulty of creating playful representation of domain-specific abstract concepts, this study discusses the design of Prime Slaughter, a computer game aimed at facilitating individual sense-making of abstract mathematical concepts. Specifically the game proposes a transposition of primality and factorization into playful interactions, addressed to primary and early secondary school children. Taking into account individual needs expressed by children regarding play, during a participatory design processes aimed at enhancing learning in museums, Prime Slaughter allows for multiple forms of play and their integration. A simple working prototype has already been developed; it will be tested and re-designed through participatory
workshops, involving a group of children in our target group.