Unrpyc, the Ren'Py script decompiler

Unrpyc is a tool to decompile Ren'Py (http://www.renpy.org) compiled .rpyc script files. It will not extract files from .rpa archives. For that, use rpatool or UnRPA.

Status

Usage

This tool can either be ran as a command line tool, as a library, or injected into the game itself. To use it as a command line tool, a local python installation is required. To use it for its default function (decompiling) you can simply pass it the files you want to decompile as arguments, or pass it the folder containing them. For example, python unrpyc.py file1.rpyc file2.rpyc or python unrpyc.py folder/.

Additional features

Translation:

For easier reading of decompiled script files, unrpyc can use translation data contained in a game to automatically convert the emitted script files to another language. You can find the supported languages for a game by looking in the game/tl folder of said game (None being the default)

To use this feature, simply pass the name of the target language (which has to match the name found in the tl folder) with the -t/--translate option. For example, if a game has a folder path/to/renpyapp/game/tl/french, then you can run the command: python unrpyc.py /path/to/renpyapp/ -t french

Raw ast view:

Instead of decompiling, the tool can simply show the contents of a rpyc file. This is mainly useful for bug reports and the development of unrpyc. You can pass the -d/--dump flag to activate this feature.

Note: this generates a lot of output.

Compatibility

You are currently reading the documentation for the master branch of this tool. Ren'Py switched to using Python 3 in Ren'Py 8. This required significant changes to the decompiler, and necessitated splitting it into two to maintain support for older games. Development and releases for this tool are now split into the master branch (Unrpyc v2.x, using Python 3) and the legacy branch (Unrpyc v1.x, using Python 2). Additionally, support for some very ancient Ren'Py features has been dropped from the master branch to simplify continued development of unrpyc. In practice this means that games before Ren'Py 6.18.0 are no longer supported by the master branch, and games from before 6.99.10 should use the --no-init-offset option. Any game using Ren'Py versions before 6.18.0 should instead use the legacy branch of unrpyc, which supports up to and including Ren'Py 7.

When using the injectors (un.rpyc, un.rpy, bytecode.rpyb), compatibility is more stringent, as these tools use the python version bundled by Ren'Py. Use un.rpyc v2 (2.*.*) for Ren'Py 8 games, and un.rpyc v1 (1.*.*) for Ren'Py 7 and 6.

Summarized:

• unrpyc v2:

  • Requires python 3.9 or above to work.
  • Releases use version numbers 2.x
  • Uses branches master for the last release, and dev for development.
  • Command line supports Ren'Py 8.x (most recent) down to 6.18.0 (below 6.99.10 requires option --no-init-offset)*
  • Injectors (un.rpyc and friends) support only Ren'Py 8.x

• unrpyc v1:

  • Requires python 2.7 to work.
  • Releases use version numbers 1.x
  • Uses branches legacy for the last release, and legacy-dev for development.
  • Command line supports Ren'Py 7.x (most recent) and Ren'Py 6.x.
  • Injectors (un.rpyc and friends) support Ren'Py 6.x and 7.x.

Ren'Py 5 or earlier are not supported currently.

Command line tool usage

Depending on your system setup, you should use one of the following commands to run the tool:

python unrpyc.py [options] script1 script2 ...
python3 unrpyc.py [options] script1 script2 ...
py -3 unrpyc.py [options] script1 script2 ...
./unrpyc.py [options] script1 script2 ...

Options:

$ py -3 unrpyc.py --help
usage: unrpyc.py [-h] [-c] [-d] [-p {1,2,3,4,5,6,7,8,9,10,11,12,13,14,15}]
                 [-t TRANSLATION_FILE] [-T WRITE_TRANSLATION_FILE]
                 [-l LANGUAGE] [--sl1-as-python] [--comparable] [--no-pyexpr]
                 [--no-init-offset] [--try-harder]
                 [--register-sl-displayable SL_CUSTOM_NAMES [SL_CUSTOM_NAMES ...]]
                 file [file ...]

Decompile .rpyc/.rpymc files

positional arguments:
  file                  The filenames to decompile. All .rpyc files in any
                        directories passed or their subdirectories will also
                        be decompiled.

optional arguments:
  -h, --help            show this help message and exit
  -c, --clobber         overwrites existing output files
  -d, --dump            instead of decompiling, pretty print the ast to a file
  -p, --processes
                        use the specified number or processes to
                        decompile. Defaults to the amount of hw threads
                        available minus one, disabled when muliprocessing is
                        unavailable.
  -t TRANSLATION_FILE, --translation-file TRANSLATION_FILE
                        use the specified file to translate during
                        decompilation
  -T WRITE_TRANSLATION_FILE, --write-translation-file WRITE_TRANSLATION_FILE
                        store translations in the specified file instead of
                        decompiling
  -l LANGUAGE, --language LANGUAGE
                        if writing a translation file, the language of the
                        translations to write
  --comparable          Only for dumping, remove several false differences
                        when comparing dumps. This suppresses attributes that
                        are different even when the code is identical, such as
                        file modification times.
  --no-pyexpr           Only for dumping, disable special handling of PyExpr
                        objects, instead printing them as strings. This is
                        useful when comparing dumps from different versions of
                        Ren'Py. It should only be used if necessary, since it
                        will cause loss of information such as line numbers.
  --no-init-offset      By default, unrpyc attempt to guess when init offset
                        statements were used and insert them. This is always safe
                        to do for ren'py 8, but as it is based on a heuristic it
                        can be disabled.
                        The generated code is exactly equivalent, only slightly more cluttered.
  --try-harder          Tries some workarounds against common obfuscation
                        methods. This is a lot slower.
  --register-sl-displayable SL_CUSTOM_NAMES [SL_CUSTOM_NAMES ...]
                        Accepts mapping separated by '=', where the first
                        argument is the name of the user-defined displayable
                        object, and the second argument is a string containing
                        the name of the displayable,potentially followed by a
                        '-', and the amount of children the displayable
                        takes(valid options are '0', '1' or 'many', with
                        'many' being the default)

You can give several .rpyc files on the command line. Each script will be decompiled to a corresponding .rpy on the same directory. Additionally, you can pass directories. All .rpyc files in these directories or their subdirectories will be decompiled. By default, the program will not overwrite existing files, use option -c to do that.

This script will try to disassemble all AST nodes. In the case it encounters an unknown node type, which may be caused by an update to Ren'Py somewhere in the future, a warning will be printed and a placeholder inserted in the script when it finds a node it doesn't know how to handle. If you encounter this, please open an issue to alert us of the problem.

For the script to run correctly it is required for the unrpyc.py file to be in the same directory as the modules directory.

Game injection

The tool can be injected directly into a running game by placing either the un.rpyc file or the bytecode.rpyb file from the most recent release into the game directory inside a Ren'Py game. When the game is then ran the tool will automatically extract and decompile all game script files into the game directory. The tool writes logs to the file unrpyc.log.txt.

Library usage

You can import the module from python and call unrpyc.decompile_rpyc(filename, ...) directly.

warning: this has changed with python 3 and might not work. This is under active development.

Notes on support

The Ren'Py engine has changed a lot through the years. While this tool tries to support all available Ren'Py versions since the creation of this tool, we do not actively test it against every engine release. Furthermore the engine does not have perfect backwards compatibility itself, so issues can occur if you try to run decompiled files with different engine releases. Most attention is given to recent engine versions so if you encounter an issues with older games, please report it.

Additionally, with the jump to python 3 in Ren'Py 8, it became difficult to support all Ren'Py versions with a single tool. Therefore, please consult the compatibility section above to find out which version of the tool you need.

Issue reports

As Ren'Py is being continuously developed itself it often occurs that this tool might break on newer engine releases. This is most likely due to us not being aware of these features existing in the first place. To get this fixed you can make an issue report to this repository. However, we work on this tool in our free time and therefore we strongly request performing the following steps when making an issue report.

Before making an issue report:

If you are making an issue report because decompilation errors out, please do the following. (If there's simply an error in the decompiled file, you can skip these steps.)

1. Test your .rpyc files with the command line tool and both game injection methods. Please do this directly, do not use wrapper tools incorporating unrpyc for the report.
2. Run the command line tool with the anti-obfuscation option --try-harder.

When making an issue report:

1. List the used version of unrpyc and the version of Ren'Py used to create the .rpyc file you're trying to decompile (and if applicable, what game).
2. Describe exactly what you're trying to do, and what the issue is (is it not decompiling at all, is there an omission in the decompiled file, or is the decompiled file invalid).
3. Attach any relevant output produced by the tool (full command line output is preferred, if output is generated attach that as well).
4. Attach the .rpyc file that is failing to decompile properly.

Please perform all these steps, and write your issue report in legible English. Otherwise it is likely that your issue report will just receive a reminder to follow these steps.

Feature and pull requests

Feature and pull requests are welcome. Feature requests will be handled whenever we feel like it, so if you really want a feature in the tool a pull request is usually the right way to go. Please do your best to conform to the style used by the rest of the code base and only affect what's absolutely necessary, this keeps the process smooth.

Notes on deobfuscation

Recently a lot of modifications of Ren'Py have turned up that slightly alter the Ren'Py file format to block this tool from working. The tool now includes a basic framework for deobfuscation, but feature requests to create deobfuscation support for specific games are not likely to get a response from us as this is essentially just an arms race, and it's trivial to figure out a way to obfuscate the file that blocks anything that is supported right now. If you make a pull request with it we'll happily put it in mainline or a game-specific branch depending on how many games it affects, but we have little motivation ourselves to put time in this arms race.

https://github.com/CensoredUsername/unrpyc