A game system projectively transforms a plurality of polygons, which form three-dimensional object located in an imaginary three-dimensional space, to a viewpoint coordinate system to draw the polygons on a projection plane. The game system includes a polygon drawing unit for drawing a polygon with a first texture which affects drawing of other texture; a second texture drawing unit for drawing a second texture, prepared in advance, on the polygon drawn by the polygon drawing unit based on two-dimensional coordinates of the second texture; and a texture moving unit for simulatively moving the second texture, drawn by the second texture drawing unit, on the polygon drawn by the polygon drawing unit by varying the two-dimensional coordinates in time-series.