Super Mario Bros. 2j is a side-scrolling, platformer action game originally released in Japan on the Famicom Disk System and is similar in style and gameplay to the original 1985 Super Mario Bros., save for an increase in difficulty. As in the original, Mario (or Luigi) venture to rescue the princess from Bowser. The player jumps between platforms, avoids the enemy and inanimate obstacles, and collects power-ups like the Mushroom (which makes Mario grow), the Fire Flower (which lets Mario throw fireballs), and the Invincibility Star. Unlike the original, there is no two-player mode and the player chooses between the twin plumbers, who are differentiated for the first time, at the title screen. Luigi, designed for skilled players, has less ground friction and higher jump height; while, Mario is faster.
The game's difficulty picks up near the end of the original and progressively increases. Super Mario Bros. 2j introduces obstacles including poison mushrooms, level warps that set the player farther back in the game, and wind gusts that redirect the player's course mid-air. Some of the game requires "split-second" precision. There were also some graphical changes, though the soundtrack is identical. After each boss fight, Toad tells Mario: "Our princess is in another castle." The main game has 32 levels across eight worlds and five bonus worlds. A hidden World 9 is accessible if the player does not use a warp zone. Bonus worlds A through D are accessible when the player plays all the way through the game 8 times, for a total of 52 levels.