The mode is where the player travels through all thirty two levels to collect five Red Coins and some Yoshi Eggs. To get the Yoshi Egg, the player must find the secret hidden block.
Differences from the original
The player is able to save the game.
There is the Toy Box which is full of minigames such as "Fortune Teller". It also has pictures which you can print out using the Game Boy Printer.
Glitches and bugs have been fixed, such as the "Minus World" glitch.
There is a mode of play called "You Vs. Boo" where you race against Boo in eight different stages.
There is a photo album were you can unlock pictures of things like Goombas and Mario and write a caption underneath. You could also print them out using the Game Boy Printer.
Instead of the image being smaller, Mario and Luigi are bigger, and only part of the image is visible. But you can move up and down to see above and/or below Mario/Luigi, and use the select button to see to the left and right of Mario/Luigi.
As well as the original Super Mario Bros. game, there's also the Challenge mode, where you play the levels you unlocked freely, and try to get five Red Coins, one Yoshi Egg, and the high score.
All of the levels have been altered, including changing various enemies.
Luigi's normal palette has changed. In the original, Luigi wore a white hat and green shirt with white overalls and Fire Luigi looks exactly like Fire Mario. In this game, Luigi's normal palette is changed to mirror that of Mario's normal palette, but with green replacing red and his original normal palette was used as Fire Luigi's palette.