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About oracles-disasm

This is a complete, documented disassembly of Oracle of Ages and Seasons for the Gameboy Color. When combined with LynnaLab, it is a level editing suite.

This repository builds US version ROMS. JP and EU versions are not supported.

See the wiki for detailed setup instructions.

Required tools to build

  • Python 3
  • python3-yaml (python module)
  • WLA-DX v9.11
  • Windows only: Must use either Windows Subsystem for Linux or Cygwin.

Note: WLA v9.11 will not produce an exact matching Seasons ROM due to quirks with how empty space is handled. Use this branch if you want an exact copy of the Seasons ROM. The game will still work either way, though.

Build instructions

Once the dependencies are installed, running make will build both games. To build a specific game, run make ages or make seasons. (Don't try "make ages seasons"; make will try to build them in parallel which doesn't currently work).

By default, the rom is built with precompressed assets, so that an exact copy of the original game is produced. In order to edit text, graphics, and other things, switch to the "hack-base" branch. Alternatively, run the "./" script in the root of the repository. This will switch the build mode to "modifiable" instead of "precompressed".

There are 4 build directories (for ages and seasons, vanilla or editable) which are symlinked to the "build" directory depending on which game is built for which mode.

See the wiki for detailed setup instructions.

Tools needed to generate documentation

Type "make doc" to generate documentation, which may or may not work at this point.

  • Perl
  • Doxygen
  • Graphviz for call graphs

Graphics files

(Note: Graphics editing will only work if you're on the "hack-base" branch or have disabled the use of precompressed graphics)

Graphics are stored as 4-color indexed PNG files. Other formats (RGB) are supported, as long as you stick to using the original 4 colors. But the indexed format works particularly well with editors such as Aseprite, which show you the 4-color palette available to you.

Some graphics have a corresponding .properties file (ie. spr_link.png has These are YAML files which specify certain properties about how they should be converted from PNG format to BIN (raw) format, and vice-versa.

The following parameters are accepted in .properties files:

  • width (int): Width of the resulting PNG file, in tiles. Only affects .BIN -> .PNG conversion.
  • interleave (bool): Whether to treat the image with an 8x16 layout instead of an 8x8 layout (mainly for sprites).
  • invert (bool): Whether to invert the color order of the PNG palettes. When "false", the order is light-to-dark (white = color 0). When "true", the order is dark-to-light (black = color 0).
  • tile_padding (int): Number of tiles of padding at the end of the image. This many tiles will be truncated before conversion to .BIN format, or this many tiles will be added during conversion to .PNG format.
  • format (string): Set this to "1bpp" for 1 bit-per-pixel files (only the font uses this).

Sprite graphics files (files beginning with spr_ instead of gfx_) are assumed to have the properties invert: true and interleave: true. However, these can be overridden by creating a .properties file.

If you wish to edit the files in raw .BIN format with an editor such as YY-CHR, run the following command from the root of the repository (using spr_link.png as an example):

python3 tools/gfx/ auto gfx/common/spr_link.png

This will create gfx/common/spr_link.bin, a raw 2bpp gameboy image. However you shouldn't have both a .bin and .png file with the same name; this will confuse the Makefile rules. You can simply remove gfx/spr_link.png, in which case the disassembly will read from gfx/spr_link.bin instead. Or, you may convert it back to PNG when you're done, then delete the .bin file. The following command will convert the .bin file back to .png:

python3 tools/gfx/ png gfx/common/spr_link.bin

Both of these commands will check the .properties file, if it exists, to decode and encode the image properly.


The reverse-engineered code and assets in this repository belong largely to Capcom and Nintendo. While I can't really stop you from doing what you want with it, I strongly disavow its use for any commercial purposes. The purpose of this project is to research the inner workings of the Zelda Oracle games and facilitate the creation of non-commercial ROM hacks.

Scripts which do not contain any Nintendo/Capcom code (ie. python scripts in the "tools/" folder) may be considered "public domain" unless stated otherwise.