I fully agree with this. I remember playing Ninja Gaiden and at the time I never really realized why I liked it so much. Looking back now it was because it really was something I had to focus on to beat. There's so many games out now that I can just stroll through and not even have to learn anything about because it's so bloody easy. I know I've had several times during games when I've made it to the end and then just for kicks I start learning combos on the end boss.