1. A game machine, comprising: field producing means for setting a three-dimensional virtual space where world coordinates are set in a memory and for producing a field which is comprised of two or more stages connecting with each other on said world coordinates; character locating means for respectively locating two or more characters appearing in a game in said stages in said field; operation character locating means for locating an operation character operable by a player through a controller in said stage of said field; character density computing means for computing a character density in said stage where said operation character is located; character density judgment means for judging as to whether or not said computed character density is lower than a predetermined character density; short character number computing means for computing a number of short said characters when said character density was judged to be lower than said predetermined character density; short character extracting relocation means for extracting said computed short characters from said stages other than one where said operation character is located, and for relocating said short characters in said stage where said operation character is located; and image display means for displaying an image of said stage where said operation character is located on a monitor.