About
Super Mario Bros.: The Lost Levels (Super Mario Bros. 2 in Japan) is a 1986 Famicom Disk System platform game from Nintendo, a much harder sequel to the original Super Mario Bros. featuring the Poison Mushroom, level warps, and a differently-controlling Luigi, across 32 levels in eight worlds plus 20 bonus levels. This is a disassembly of Super Mario Bros. 2 Japan's program files, originally created by a reverse-engineer known as doppelganger, adapted here to work with the CC65 assembler (the original used asm6). It's provided as separate assembly source files, one per set of worlds plus the ending, that reassemble the game, though the necessary character ROM graphics files must be supplied by the user from their own copy.
Getting started
Each assembly file corresponds to a portion of the game and can be assembled independently; a batch script is included to chain all the steps together and produce a final disk image, provided the user supplies their own character ROM files from the original release.
History
The disassembly was originally created by doppelganger, building on an earlier SMB2j reverse-engineering effort by Beneficii and drawing on techniques from a prior Super Mario Bros. 1 disassembly project, since the two games share an almost identical engine.