I like how everyone ignored my post about the Tiger LCD Sonic 1 & 2 games that are single screen. All you have is a moving platform and enemies that constantly appear with what acts like Sonic basically "running on a treadmill." The background is static and none of the graphics actually scroll. One could easily remake those games and just apply a more detailed background. Instead of creating the illusion that Sonic is actually running along moving ground represented by black lines, take that away and have it more like the badniks are swarming in on you with Dr. Robotnik attacking you at the end of the stage. Like Mario Bros. the goal is survival and racking up points. Have faster, harder to hit enemies like Shellcrackers, Rollers and Yadrins attack in patterns that make it more difficult to clear later levels. You'll have a fixed screen arcade style game easily.