Super Mario Bros. is divided into eight worlds, each of them with four levels. Mario has to get to the end of the level by jumping over various gaps and avoiding the enemies on his way. Mario can use several platforms (some of them collapse when Mario lands on them), stairs in the level, as well as Jumping Boards. There are also pipes along the way, some of which Mario can enter to visit various secret coin rooms before returning to the level, a bit further ahead than when he left.
Enemies include Goombas, Koopa Troopas, Buzzy Beetles, Koopa Paratroopas, Bullet Bills, Hammer Bros., and jumping Cheep-Cheeps. All these enemies can be defeated when Mario jumps on them. Koopa Troopas and Buzzy Beetles cower in their shell when jumped on, which Mario can kick to defeat other enemies with. Koopa Paratroopas lose their wings and fall to the ground when Mario jumps on them. Other enemies include Piranha Plants, the Spiny-throwing Lakitus and the Hammer Bros., and Mario has to either shoot fireballs at them or just avoid them. There are a few levels which take place underwater. In the water, Mario can swim freely from the top to the bottom of the screen. The enemies in underwater levels are Bloobers and Cheep-Cheeps. Mario can only defeat these creatures by shooting them with fireballs.
Mario swimming in a water level.
If Small Mario takes a hit, falls down a pit, or if the Time Limit runs out, he loses a life, and restarts the level. The point where Mario continues depends on how far he ran through the level before getting defeated; either from the beginning, or at one of several invisible "checkpoints" throughout the level.