Here is a talk by the creator of the brilliant 8-bit platforming game Jumpman (who isn’t Mario). That’s all the lead-in I have time to provide right now. And if you get the chance to try Jumpman, do it. There’s a version on Steam! (Note, the C64 version is preferable to the DOS version.)
The Man Behind Jumpman: Retro Gaming Revealed (Youtube, 58 minutes)