At a time when the classic 2D-sidescroller style of Mario games was thought to be dead and gone, New Super Mario Bros was a refreshing change of pace and showed Nintendo that the original style was still viable and could be massively successful -- and it was, for better or for worse. But I will talk about that in the reviews for the later games of this style. The game was a lot of fun and changed up the classic style in an interesting way. The difficulty progressed reasonably and by World 8 was reasonably difficult without feeling unfair. I still go back to it on occasion and 100% it. Here's an interesting thing, there is a hidden challenge mode that you input a code for. What it does is it makes the game like the classic sidescrolling Mario games and prevents the player from backtracking through the level.