A game ball is disclosed that includes a polymer foam layer processed with an inert fluid blowing agent, such as nitrogen. The polymer foam may be a polyolefin material, such as polyethylene, polypropylene, and ethylvinylacetate, and the inert fluid blowing agent may have a relatively high-purity. The polymer foam may be manufactured with a process that includes impregnating a polymer with the inert fluid blowing agent and expanding the polymer by heating the polymer above a softening temperature of the polymer, reducing a fluid pressure surrounding the polymer, and cooling the polymer. The game ball may be a soccerball, football, or volleyball, for example, that includes the polymer foam.