This is a ROM hack of Super Mario Bros. starring plumbers Jario and Duigi. Choose either Jario and Duigi, each equipped with a different set of physics, and set out to save the Mushroom Princess from King Trowser. In their quest, they will have to journey through four brand-new worlds filled with new setpieces and enemies lurking around every corner. Do you have what it takes to rescue the Mushroom Kingdom?

This ROM hack was made with speedrunning in mind, and makes several changes to allow for a unique experience:
-The 21-frame "framerule" is no longer used to determine when to end a level, meaning that every frame matters in each and every level.
-You can lower the flagpole from behind if you are facing left while grabbing the flagpole, much like you can in the Super Mario All-Stars version of Super Mario Bros.: The Lost Levels.
-The 2 player game feature was replaced with a character select. Jario controls identically to Mario and Luigi in the original Super Mario Bros., while Duigi is heavier, accelerates faster, jumps lower, and cannot climb vines. While Duigi provides an added challenge due to his limitations, his unqiue characteristics make certain techniques like the flagpole glitch easier to perform.
-The game's 17 new levels were designed for speedrunners to blaze through. A warp zone in 1-3 to World 3, a warp zone in 2-4 to the hidden World 5, and a warp zone in 3-2 to World 4 allow for skilled players to skip some of the game's stages.
-In World 5-1, the player will have reduced gravity. This affects both jumping and swimming controls.

v1.1 Revision Details:
-Errors with 4-4 ending sequence corrected (Mushroom Princess and all ending text now appear).
-World select is no longer enabled after completing 5-1 in order to keep the All Levels route more interesting.
-Duigi is no longer erroneously referred to as Jario on the Game Over screen.
-Trowser no longer appears as a Spiny when killed with fireballs.
-Minor change to World 4-3 made to prevent player from possibly being stuck until a time up.
-New inputs recorded for the title screen demo.