Super Mario Bros

Super Mario Bros is a platformer game for the Famicom/NES.

NES version

 * APZPOG, weird level
 * EKGAIS, cartoony graphics
 * GAYSUK, delay Mario's falling gravity when you walk off edges
 * KAGKAL, unbelievably fast goombas
 * KOYNAN, no sound when Mario jumps
 * LUGLUG, star dribbles in fixed position
 * NAPSIN, a fireball launch kills all enemies on screen
 * NEPELA, grayscale graphics
 * NLLNYY, weird music
 * NULTKA, all enemies are Toad.
 * PIGNAX, invisible Mario
 * PIGPOG, spawns random enemies and obstacles
 * STAGEO, all enemies throw hammers
 * VILLGI, Mario walks backwards
 * YEAAAA, a disco-like lite show and other glitch graphics
 * ALASKA, every item functions as a star
 * NEEDLE - Corrupts all graphics
 * AEPLLG - Jump multiple times
 * GIIIVY/AISSON - Go through objects

Super Mario All Stars version

 * 008C1E:01, Enables debug mode. A turns you Super, X turns you into Fire Mario, and Select enables free-movement mode (allows you to move through pipes, bricks, etc.), doesn't make you safe from enemies though.