Super Mario Bros. is a hardcore platforming classic. It redefined the entire video game industry after the market crashed. It still is one of the toughest games of all time. The first game also had an unforgettable vibe that no other game had. The music was catchy. The graphics were bright and colorful. The controls were extremely responsive.
The game seemed to last forever, or at least until the end of level 8-4. Getting there is the hard part--only a true champion can get there without save states or handicaps. This is still my favorite Mario game of all time.