We present a flow-based watercolor rendering scheme for game background images. Our scheme is composed of two stages: a flow-based abstraction stage, which is followed by a noise-based watercoloring stage. In the abstrction stage, we apply a 3D Sobel filter to accelerate the abstraction process. The abstracted image is then applied a Perlin noise-based watercoloring process to produce watercolor effects. Finally, we apply paper texture to improve the realism of the results. Among various categories of photographs, our scheme shows good results on portraits, which is a common background of game scene. We apply our scheme for several game backgrounds and produce visually pleasing watercolor effects from them.