I think I first encountered this game as a pack-in via Super Mario All-Stars and was incredibly confused by it. The term "romhack" didn't even exist at that time, but that's what it felt like to me. What do you mean I can't jump on a koopa to kill it? The controls are always what killed this for me. Mario would either refuse to jump sideways without getting some momentum first, or if you did start moving, you'd soon be floating away to the edge of the screen. The overall gameplay concept was never really all that fun either.