Yeah that's what I though I'd do. make it like a simply, you see mario with a gun sprite, then have controls being left right and up(jump) and 2nd is shoot. then just have a floor laid out and have goombas coming from the right and increasing in number. could be potentially a great stress reliever! I have all the controls down, and the Goombas, I just need a better mario looking sprite, and enemy movement.