Getting started

Before setting off on your modding journey, it’s important to know some terms—M&L jargon, if you will—as well as the basics of NDS ROM structure and modding. Most tools support all region ROMs of the game.

Terms

• Script, scripting, scripting language, AI: The Mario & Luigi games up until Brothership utilize a custom scripting system/language. It is always stored as binary, but can be recognized by its abundance of blocks of 00 00 00 00 bytes and other small little-endian 32-bit values (the command parameter variables bitfield). Although the language itself is the same, the game uses 4 different sets of commands, referred to as dialects, used in different contexts. Commands 0x0000–0x0046 (incl.) are the same for all dialects. The Battle, Menu and Shop scripts are internally referred to as AIs in the game’s filenames (BAI, MAI, SAI), code (clBtlAIBase, clMenuAIBase, clShopAIBase), and debug messages.

  • FEvent script, Field Event script: This dialect is used for all scripts in the overworld. All of its scripts are stored in FEvent/FEvent.dat, which also includes the messages (dialogue) used by these scripts, as well as data for things like the actors in every room.
  • Battle script, BAI script: This dialect is used for, well, everything within battles. Its scripts are stored in the BAI/BAI_*.dat files, while its messages are stored in BAI/BMes_*.dat.
  • Menu script, MAI script: Surprise surprise, this dialect is used for scripts in menus. Its scripts are stored in the MAI/MAI_*.dat files, while its messages are stored in MAI/MMes_yo.dat.
  • Shop script, SAI script: You’re not going to believe this, but this dialect is used for scripts in shops. Its scripts are stored in SAI/SAI_tuto_yo.dat, while its messages are stored in SAI/SMes_yo.dat.

• Command, scripting command: Commands are the basic building blocks of scripts. Each command can do something lower-level like “Jump” (moves the command pointer), “Add”, “Multiply”, or higher-level like “Show Textbox”, “Wait for Textbox to Close”, “Load Music File”, etc. Commands are usually referred to in hex and prefixed with the dialect they exist in:

  • CM_: Common commands (0x0000–0x0046 incl.), existing in all dialects.
  • FE_: FEvent commands.
  • BA_: Battle (AI) commands.
  • MA_: Menu (AI) commands.
  • SA_: Shop (AI) commands.

  For example: CM_0001, FE_01BA, BA_0077.

• Language table: Language tables contain text localized in multiple languages, hence the name, and occasionally binary data like fonts as well. They usually end with padding.

• Text table: An entry in a language table, contains multiple text entries, all in the same language.

• Debug messages, debug prints, notes, footer notes: These are internal messages that the developers left behind within the footers of the scripts. They are referenced by commands which do nothing in the release build of the game, which suggests that they were printed to the developers’ debug console, but this is not confirmed. They are in Japanese, encoded in Shift JIS. You can find an automatically-generated dump of them here (currently only contains messages from FEvent and Battle scripts). Get your translator handy!

Let’s get modding!

Depending on what you want to mod, you’re going to need different tools.

Scripts & Text

mnlscript.py is the recommended tool for editing scripts and text that converts the M&L scripting language into Python and back. Although that may sound intimidating, it tries its best to be as readable as possible.

QtMnL is a GUI editor that supports editing the ROM directly. However, it is outdated and missing many basic features.

Graphics

Spritoglobin is a tool that allows you to view sprites, with editing support being worked on. It currently only supports the US and EU versions.

Maps

A Tiled plugin for editing maps is currently being worked on.

Audio

The game’s audio, like music and sound effects, is stored in Sound/sound_data.sdat. This is probably the one format used by the game that isn’t specific to the M&L series, so you don’t need any specialized tools to edit it. You can use established ones like Nitro Studio 2 (Deluxe).

Distributing your work

So you’ve worked hard on you mod, and it’s finally finished! Or at least, finished enough for an alpha version you want people to check out. So you just upload the entire ROM, right?

So how do you create a patch file, you ask? Well, one format you can use is Xdelta3. Although the official program is CLI-only, there are many GUI tools for both creating and applying Xdelta3 patches.

Make sure to tell your users which region of the game the patch is based on as well! Patches built from a given version can only be applied to that version.