Payoff matrix for the snowdrift game.

Digging out of the snowdrift gives each player a benefit of b/2. The cost is born by the digger (C) who splits the cost when both dig, or bears the entire cost as the sole digger. When b/2−c>0, the ESS is a mixture of C and D individuals. When b/2−c/2>0>b/2−c, All-D is the sole ESS, even though there is still a social dilemma where All-C yields higher payoffs than All-D.