Super Mario Bros. Definitive is a modification of the Japanese Super Mario Bros. 2 (also known as Super Mario Bros.: The Lost Levels) that combines all levels from said game and the original Super Mario Bros. into one ROM hack, allowing all levels from both games to be played back-to-back seamlessly. Levels from the original Super Mario Bros. are played first, with levels from The Lost Levels immediately following the final Super Mario Bros. level. In addition to including every level from both games, Super Mario Bros. Definitive makes several small tweaks to the levels and game engine, most of which come from Super Mario All-Stars or All Night Nippon Super Mario Bros. Super Mario Bros. Definitive uses the MMC3 mapper and is based on the codebase from recent NES conversions of Super Mario Bros.: The Lost Levels. Check out the description on RomHack Plaza for additional information about this hack!
Simplistic6502 - Programming, custom title screen, save system SeraphmIII - Programming, World 9 levels, minor fixes