I am not a fan of demakes because they are never done by anyone who actually lived in the 8 and 16 bit era. Critical errors of demakes:
1) too much animation. Only the neo geo did heavy animation.
2) object resolution may be accurate but its rendered in high resolution causing unreasonable hq levels of scrolling.
3) color pallets are just all wrong.
4) rarely uses proper audio chips.
5) Gameplay that would never pass the first wave of brainstorming in the actual game.