Skip to content


Switch branches/tags


Failed to load latest commit information.
Latest commit message
Commit time

((DE)C)onstructor for (A)pps (DECA)

"Everything should be built top-down, except the first time." - Alan Perlis

Code contributions are more than welcome!!!

A hacked up tool for exploring/extracting/modding files from Avalanche Studios APEX engine files, mainly Generation Zero.

Written in Python, tested only on Linux, code is a mess, because this is an experiment...

(Pre-)Releases for Windows

Development Releases are on the Discord


For deca specific and general GenZero, theHunter:COTW, and other APEX engine games modding. Also has a channel for development releases of deca

Maps and data mining created with DECA

Generation Zero


Key Features

  • Export (modelc, meshc, hrmeshc) to GLTF 2.0 (material models not complete/missing, no bones)
  • Export ADF encoded spreadsheets
  • Export textures to PNG
  • Parsing most ADF files (Gen Zero)
  • GUI to explore archive files
  • Basic rebuilding of archive files to update textures, Characters/Machines work. Set pieces do not.

"Supported" Games

Support varies among the games, people are activily using deca for GenZero and theHunter:COTW

Studio GAME
Avalanche Studios / Systemic Reaction Generation Zero®
Avalanche Studios / Expansive Worlds theHunter™: Call of the Wild
Avalanche Studios Just Cause 3
Avalanche Studios Just Cause 4
Avalanche Studios RAGE 2
Avalanche Studios / Systemic Reaction Second Extinction

Quick Start

No installer, just unzip the release file in some directory and start deca_gui.exe. (not signed so windows will complain) Go to the menu and under File select New Project ..., find theHunter EXE, and wait 40 minutes the first time. It does a bunch of work to figure out possible file names, and python multiprocessing on Windows is a pain.

It will uncompress all the compressed sections of the archives and place them into "__ CACHE __" in the project directory.

It currently creates a work/hp directory one directory above where deca_gui.exe is. So you can used File/Open Project and find the project.json file to open it again. Ignore the log tab on the left and take a look at the DIR tab, which shows the entry VFS layout. Double click on nodes and the contents (if deca can parse them) appears in the tables on the right.

Individual files can be extracted with the EXTRACT button after they are selected with one click. They are placed in the project directory under "extracted". Folders can be extracted recursively so be careful unless you want to expand gigabytes of data.

Modding is a work in progress, files are extracted with the PREP MOD button and placed in the "mod" sub-directory. BUILD MOD will then package up all the files in the mod directory (which you can/must edit by hand right now) and places the results into the "build" sub-directory. The build directory contents can then be copied to the normal "dropzone" folder like in JC3 (I have not tested it with theHunter, only GZB, and even then all I know is that the game does not crash before it gets to BETA over screen)

Game Support

File Type Status (Numbers are arbitrary)

FILES Status Notes
AAF Done
ADF Extractable, Parsed Partial Handling of GameDataCollection (0x178842fe)
Export of modelc, meshc, hrmeshc, mdic to GLTF 2.0 (material models not correct?, missing bones)
Missing code for types that have hardcoded parsers in EXE(?)
stringlookup not fully grokked
RTPC Extractable, Parsed
OGG Extractable Ogg file, can be extracted
CFX Extractable Autodesk Scaleform
.obc Extractable found a correlation in file size, guess at record size/count
RIFF Extractable
lFSB5 Extractable
RBMDL Extractable
TAG0 Extractable
btc Extractable

External Dependencies


Gibbed's Just Cause 3 archive exporter

Learned about ALL the files here and used as a basis to understand changes made in GZ.

Big thanks to Gibbed for creating and sharing his work!!!

Timothée Feuillet's fork of Rick Gibbed's tools

This filled in some holes for the ADF parsing "A Fork of the Just Cause 3 tools by Rick Gibbed"

Lukas Cone (PredatorCZ) Apex Tools

This has information about how stranger AmfBuffer formats are "compressed"

Various Microsoft(tm) websites

Got most of the info for parsing the custom image formats came from the source documentation for DirectX

CFX Decompiler

I don't have to worry about the CFX files because of this!

For map generator and viewing files locally with pouchdb

add this to chrome command line

--allow-file-access-from-files --allow-file-access --allow-cross-origin-auth-prompt


Script to turn off normal smoothing

for object in bpy.context.scene.objects:
    if object.type == 'MESH': = False

Kaitai Format

Format files for .gfx for string extraction and older (for GZ and COTW) non RTPC world.bin files are provide with Kaitai description files. Kaitai links Main, IDE, docs

Disclaimer (IANAL)

All product names, logos, and brands are property of their respective owners. All company, product and service names used in this website are for identification purposes only. Use of these names, logos, and brands does not imply endorsement.