Morality is concerned with the distinction between "good" and "evil" or (more objectively) with the distinction between right conduct and wrong conduct in a given situation.
When moral theorizing in a social context, competitive and complementary forces need to be accounted for - and game theory is excellent for this. Game theory is based upon models of rational decision making, and morality is all about deciding what one "ought to do" in any given situation.
Evolution teaches us that the species (or groups) most likely to succeed and survive are the ones which are able to make the best rational decisions resulting in the greatest overall benefit for that species (or group). Moral good may be viewed as simply that set of social rules of "right and wrong" which results in the greatest overall benefit for a given group.