You control a character named Bros, who must save the princess and restore peace to the kingdom. You must travel on land, underground, and through the sea. You will face a variety of enemies, including Goombas, Koopa Troopas, and Bullet Bills.

You can use the power-ups, or collect items, to help you. You can use the item that lets you jump and hit a block from underneath to reveal an item. This could be a coin, a mushroom, a fire flower, or a star. The mushroom provides the most important boost of power and allows you to grow to over twice your normal size and strength. It also allows you to be hit once without losing a life.