Abstract: A video game machine, which comprises a CPU for executing a program and a memory in which, based on the control provided by the CPU consonant with the execution of the program, are stored data that are read from the program and concern a plurality of characters to be displayed on a display device, provides a pseudo-sense of reality, as though a character projected on a display were a living entity. In such a video game machine, inheritance probabilities are defined for individual portions, of the data concerning a plurality of characters, that constitute the characters, and under a predesignated condition available during the execution of the program, a portion constituting one character, of portions constituting two characters, is maintained at a predetermined inheritance probability that has been defined, and data for new characters are prepared.