I looked this up as I was curious what people would say. I think the shadow is one of the hardest I have played, took me 10 years to complete the final battle however I never go for a score but to complete the game. I will never be a competition winner just enjoy knocking the balls around. Which ever machine I chose to play. I have played many machine that are hard but I have found some not that enjoyable to play. So their could be harder I just didn't necessary like them so lost interest in them.