Computer games have always been a source of entertainment for all age groups. From the point of view of game developer it has always been difficult to quantify the entertainment value of the human player, as the entertainment value is very subjective. The two factors which mainly influence the entertainment value are the type of the game and the contents of the game. In this paper we present some quantitative measures for entertainment in a genre of computer game and apply them as a guide for the evolution of new interesting games. Our experiments show that this approach has potential for further investigation.