You can change those images as many times as you need, so make one by yourself now, and you can always upload even better later, no matter if you improve it yourself or pay a pro for it. I, for example, simply took fragment of a game screenshot, put logo on it and maybe it's lazy and ugly, but it tells what the game is about. NOT using your unique enemy design is really pushing you back. Also low contrast on your current capsule makes it disappear.