As you see in these pictures, there are different color combinations i did on my game case whether it is complimentary (#3), Monochromatic (#2), or analogous (#1).  These all come from Color Theory. Color Theory is used in video games to get the right attention, attraction, and understanding or idea of a game.  Opposite colors usually attract lots pf people which is why games like Splatoon show opposite paint colors on its game case. Colors are used in a variety of ways, whether it for attraction, theme of the game, or attention. My favorite is the 3rd one with Blue and Orange as my game will be all about color, and seeing 2 opposite colors together really brings on the attention.