Hey uh here's my ideas for this project:
1) Have an option to have Mega Man style scrolling (perfect for games with no scrolling)
2) Have acceleration and deceleration for the player (and have the ability to adjust them)
3) Implemment the super mushroom from Mario (and the powerups from Mario3)
4) Have parallax scrolling (Yes I know it's hard to implemment on the NES, but it's just an idea I had lol)