When the NES was released in 1985, the US had 13 launch titles ready for it. Some were shipped with the console itself.
Super Mario Bros. was released by Nintendo in 1985. It was a quasi sequel to the arcade game of Mario Bros, Instead of arcade competition in the sewers, here, we had classic platforming action. When the NES was first released, it was the game that was packed in and shipped with the console.
Super Mario Bros set the bar for platforming games for decades afterwards. In fact, recent studies have shown that Mario is more recognisable than Mickey Mouse in some parts of the world. This is pure platforming fun and has a steep difficulty curve, that is designed for experienced players. However, the appeal is strong with this one, bringing in gamers of all skills to this game.