Originally, it appears that this menu would have been accessible from the '1 PLAYER' / '2 PLAYER' selection menu if player 2 was holding A + B. Apply this IPS patch to a Super Mario Bros. The menu shown in the picture was found elsewhere in the ROM and hacked into the title screen it doesn't appear if you use the Game Genie code by itself. When you start a game, your item box will be filled with one of every item plus an extra Warp Whistle, and the remaining slots will be filled with P-Wings.
Press Up or Down to select a world to start on.On Japanese, US and European versions, Game Genie code KKKZSPIU activates a level select and debug mode.