Nowadays, many computer games based on NPR(Non-photorealistic Rendering) techniques have been developed due to their distinctive visual properties. However, only limited methods of NPR techniques have been exploited in producing computer games and amongst them cartoon-style rendering techniques especially has had the special interest. In the paper, we suggest an effective rendering method of comic-book style that will be applicable to computer game. In order to do, we first characterize the properties of comic-book from comparing two visuals: celluloid animation and comic-book. We then suggest a real-time rendering method of comic-book style represented by outline sketch, tone, and hatching. We finally examine its effectiveness by observing the game developed using the method.