The article investigates the interplay of moral rules in computer simulation. The investigation is based on two situations which are well-known to game theory: the prisoner's dilemma and the game of Chicken. The prisoner's dilemma can be taken to represent contractual situations, the game of Chicken represents a competitive situation on the one hand and the provision for a common good on the other. Unlike the rules usually used in game theory, each player knows the other's strategy. In that way, ever higher levels of reflection are reached reciprocally. Such strategies can be interpreted as ‘moral’ rules. Artificial morality is related to the discipline of ‘Artificial Life’. As in artificial life, the use of genetic algorithms suggests itself. Rules of behaviour split and reunite as chromosome strings do.