Funnily enough, making a Superman game that plays like modern Sonic, but with flying, would be fitting.
>racing towards danger
>quickly dissipating enemies to keep up
>multiple routes that lead to different obstacles
>Lex, serving as the game's Eggman, has giant robots that can compete with Superman, or least, take his focus and stop him in his tracks
>can switch between 2D and 3D levels
Make a stylized, light-hearted adventure and there's an idea in there, though it wouldn't be considered AAA.